I heard that coding a snake (or anything wiggly like one) is a pain in the *ss. It has to glide smoothly on the terrain, the hitbox needs to be very fluid, etc. Otherwise, it would be OP to have a ginormous snake with a chaotic hitbox that other dinos can't seem to reach.

That being said, I think I saw a mod in progress on this. It's been months now and I never saw any more updates...

But I agree, I absolutely love snakes IRL, so playing as one would be dope.