There's a lot to the story of Devadatta if one goes back through the vast collection of suttas and their commentaries. Basically, Devadatta was the Buddha's cousin. He practiced meditation until he developed some very impressive psychic powers. Unfortunately, Devadatta became corrupted by jealousy and tried to take over leadership of the monastic order. He tried to introduce a number of changes to the Buddha's rules — one of them being strict vegetarianism — all of which the Buddha rejected. He also tried to get the Buddha to name him as his successor, and when that failed he to tried to have the Buddha assassinated on a few separate occasions (all of which failed because, according to tradition, it's impossible for the life of a Buddha to be taken by violence).
In the end, Devadatta caused a schism in the Sangha and ran off with a large number of monks. The Buddha then sent the Venerable Sariputta and Maha Moggalana to give a discourse to the rogue monks and win them back. And as for poor Devadatta, he was eventually swallowed up by the earth and fell into Avici (a nasty sounding hell realm), where, it's said, after suffering for one hundred thousand eons (kappas) he'll be reborn as a pacceka-buddha called Atthissara or a buddha named Devaraja. Or so the story goes.
As for the Buddha, he never said that simply eating meat is unwholesome. One way to look at it is that meat is just matter/materiality (rupa). In fact, it's the very same matter that makes up all things, including plants. So it's not simply the material of the food that's in question here. What is in question are the intentions behind our actions. It's these that produce either wholesome or unwholesome kamma, and unwholesome kamma is what should be considered "stench," not simply the eating of meat.
I'm sure the Buddha understood that many people lived solely because of their livestock, or the animals that they hunted. For some, it was either raise animals for food, hunt or starve. Would it have been wise to force people to abstain from eating meat if it meant that they couldn’t feed their families? Of course not. But the Buddha also respected animals and he didn't wish to see them killed, especially when it was meant specifically for him and his disciples. He also knew that many people who did give alms to the monastic community weren't always followers of the Buddha. Some were followers of the other sects, but they'd still give food to other wandering ascetics. (If they were brahmins, for instance, they'd almost certainly have meat to offer.) The dilemma was to find the middle way between the two extremes. Mendicants were expected to accept and eat only what's given to them, but the Buddha didn't want animals killed just to feed his followers; so it was in this spirit that the Buddha stated his monastics should only eat meat if it's pure in three ways:
'Jivaka, those who say "Animals are slaughtered on purpose for the recluse Gotama, and the recluse Gotama knowingly eats the meat killed on purpose for him" do not say according to what I have declared, and they falsely accuse me. Jivaka, I have declared that one should not make use of meat if it is seen, heard or suspected to have been killed on purpose for a monk. I allow the monks meat that is quite pure in three respects: if it is not seen, heard or suspected to have been killed on purpose for a monk.'
Now, this doesn't mean that the Buddha condoned the killing of animals, far from it. Let’s not forget the first precept: Panatipata veramani sikkhapadam samadiyami (I undertake the precept to give up killing living beings). Nevertheless, besides ahimsa, the main theme behind the monastic life is non-attachment. Ideally, one shouldn't be attached to any food that one eats. Whether one prefers meat, vegetables, fruits or rice, one should be content with what one is given. Food is merely to be used to sustain the body, and to keep one healthy enough to practice. In fact, the Buddha didn't want his monks and nuns to forget the importance and purpose of the four requisites (i.e., clothing, food, shelter and medicine), or their purpose in the holy life, and so everyday they're expected to contemplate the uses of all four, including food:
Pa.tisa"nkhaa yoniso pi.n.dapaata"m pa.tisevaami,
(Considering it thoughtfully, I use alms food,)
Neva davaaya na madaaya na ma.n.danaaya na vibhuusanaaya,
(Not playfully, nor for intoxication, nor for putting on bulk, nor for beautification,)
Yaavadeva imassa kaayassa .thitiyaa yaapanaaya vihi"msuparatiyaa brahma-cariyaanuggahaaya,
(But simply for the survival & continuance of this body, for ending its afflictions, for the support of the holy life,)
Iti puraa.nañca vedana"m pa.tiha"nkhaami navañca vedana"m na uppaadessaami,
([Thinking,] Thus will I destroy old feelings [of hunger] and not create new feelings [from overeating].)
Yaatraa ca me bhavissati anavajjataa ca phaasu-vihaaro caati.
(I will maintain myself, be blameless, & live in comfort.)
In addition, the tradition of going for alms is a very important practice because it ties the monastic community and lay-community together. Without this intimate bond, the two would eventually drift apart—the monks and nuns into practicing the Dhamma in some remote area and the lay-followers into delighting in sensual pleasures in the large cities. This way, they help to support one another. The lay-community offers food, clothing, shelter and medicine to the monastic community, and in turn, the monastic community offers to teach meditation and Buddhist discourses to the lay-community, thereby keeping the teachings and practices alive for future generations. If the laity ceases to support the Sangha, then the Sangha will simply cease to exist. And you can't always count on everyone offering you alms to be a vegetarian.
With that being said, what does this have to do with us? Well, in today's world, we have many more choices than they did back then. Farming and livestock raising have taken on completely different forms. In the past, animals were generally treated better because they were so important. People fed them well, watched over them and respected their sacrifice to feed their families. Today, however, they're raised in very poor conditions for the sake of sheer volume. The more you have to offer, the more people can buy and the cheaper it'll be. What we should be asking ourselves is, What can I afford to eat? If we can afford to buy enough of the right kinds of foods that we need to stay healthy, then we can try to eat no meat at all. This way, we'll contribute less to the suffering of animals.
However, if we can't do that, we can at least try to eat as little meat as possible. We can also try to buy meat from places that have higher standards for raising livestock. Organic and free range farms are popping up everywhere. Why is this important to do? Well, as a Buddhist, we should realize that animals are also sentient beings. They have rupa, and when they're alive, they also have mind/mentality (nama). They're aware. They can feel pain. They can suffer. If we do eat meat, we should at least contemplate where our food comes from, and we should respect these animals' sacrifice for our own well-being. We should eat mindfully, regardless of what we eat, where we eat and when we eat.
Not all Buddhists are vegetarian. Some are, but some aren't. No matter which we decide to choose, we should realize that our choices affect more beings than just ourselves. Eating meat is OK, but be mindful of where that food comes from and that eating it doesn't make one superior to one who doesn't. Not eating meat is also OK, but be mindful of where that food comes from and that it doesn't make one superior to one who does. The goal of the holy life is to free ourselves from greed, hatred and delusion; it's not meant for us to cling to one particular practice over another. Each person should decide what's right for them and respect the choices of others. Our choices, no matter what they are, should be carefully guiding us towards liberation, not towards being judgmental.
Just for some added perspective, I don't consider myself either a meat-eater or a vegetarian. To me, each can be easily taken on simply as a view, position or habit. One can slowly begin to feel strongly one way or the other, and that can give rise to further ego-clinging. This is true with all things, from clothing, hair styles and cars, to food, religious beliefs and musical tastes. That's why the Buddha often admonished his followers to be ever-mindful. Even if we do attach to these things, it's important that we see this. Why? Because that's how we can learn from them. Insight arises only when we observe the friction caused by our own fabrications, intentions and desires.