More/different mob heads

Like why just add mob heads just for creeper's, steves, zombies, skeletons, wither skeleton, the enderdragons head and add more of them like the zombie pigman, drowned zombie, plus most of the animals like cows pigs, sheep, lol maybe even the chickens u get what I mean. It would be better to have more than just a select few. And plus it would make builds that uses/need or want to have the mob heads in them. I mean it would be cool to have more mob heads.