I am not afraid of child avatars, nor do i hate them.
I do find however find them extremely creepy.
If you want to rp a child, by all means go for it and have fun. But children are not allowed in bars, sex clubs etc in RL so why should they be in SL?
If I go to an Adult venue, I expect I will be interacting with other adults, not dealing with an adult rp'ing a brat who can't behave. Alts are easy to make, so why not make an adult alt to go to those venues where child avatars aren't welcome?