User blog comment:Supp0rt4n00bz/Something about champion design/@comment-9939438-20130729040810/@comment-5331854-20130729092528

That and problems with making their model skeletons believable, which is harder for non-humanoid models. Even Rumble (who is a small humanoid in a humanoid vehicle) gives Riot headaches, they stated that Rumble's troublesome skeleton is making new skins as much work as making new champions (they want to put extra work in his next skin and retroactively use the skeleton of that skin for the earlier skins including basic skin, though).

I'll bet that Elise was the most challenging champ for the 3D Designers 'till today because there are 3 sorts of spiders to animate (true, you only need few animations for the spell and the spiderlings, but still).

Non-humanoids would be easier to animate in MOBAs with 2D-graphics for their champs, but the only example I know (Awesomenauts) is mostly inspired by Sci-Fi's from the 80's, where non-humanoid aliens are a rare sight, too.

Still, we have a cougar, a naga, a bird, a bear, spiders, winged people, a centaur, a half-fox (or gumiho or kitsune, still a fox with many tails), a minotaur, Skarner, an armadillo and and and (also, the void creatures are still interesting to look at). While most of them have humanoid traits, they're still different. Plus, Riot promised more monster champs, for example Daddy Kog (it's also hinted that Kassadin's daughter could be a monstrous champ), so happy news for you. Just be wary that anything female, even monsters, can and will be fanservice as long as they are in Runeterra, so some humanoid traits will always exist.