I feel I should clarify my original statement, though The Architect seems to have understood my intent. I meant
starting with a breeding pair of large food animals is useful for some embark builds, not that breeding large food animals is useful for only some forts. As assimilateur mentioned, if you're in a freezing biome embark may be the only time when you can get large food animals since they otherwise can freeze to death in the cages.
Also, given that leather is cheap and easy to import in large amounts, invaders can provide bones and skulls, and farming can provide a decent variety and plenty of quantity of food, I'll agree with The Architect; animals are not really necessary for animal-product industries. And, if one so desires, one can do without bone and leather works, so while they are of course useful they aren't, strictly speaking, necessary as such.
Anyway, back to actual questions!
Without me looking at the new version thread - is pack animals for use within your fort coming this version?
I don't believe so. I'm pretty sure that's part of the Caravan development arc, which will involve making caravans actually move about the world map instead of just appearing at your fort as well as allowing you to create caravans from your own fort. Use of pack animals, minecarts, and other material-carrying aids is suggested fairly often because of how useful and realistic it would be, but hasn't been done yet.