Like all animals, humans do have instincts. As species evolve, they continue to have instincts, but they increasingly choose how to express those instincts. This is part of moving from a primitive to a more advanced species (or state of being). It is not a matter of losing instincts, but of creating expressions of them.

You feel that urge to have sex... so do you rape or do you date?

You feel that urge to eat... so do you hunt or do you gather?

I view flesh-eating as a kind of theft. The cow eats not for you, but for itself. It is here, like we are, to live and enjoy life. It eats, digests, and grows its flesh, not so that you can come along and steal it, but so that it can live. It makes milk not for you to steal it, but to feed its calf. The cow says "get your own bag". Go find your own vegetables, digest them, and you'll have plenty of flesh on your bones and be healthier to boot. There is no need to steal the cow's flesh, and doing so is not helping you stay alive - it is killing you.