Your entitled to your opinion, but, to me, deer just don't seem right for FeralHeart.
For one thing, Kov would have to mesh them, animate them, change some of the existing coding, all that stuff, which he doesn't seem to have time for.
Another thing, if there were deer characters, anyone that was a deer would get attacked by anyone that plays as a lion or wolf, it just wouldn't be fun for them.
In my opinion, deer don't fit into the whole lion/wolf concept.
But hey, that's just me.