[Ccook50]

That's the basic stigma. The target age group is 2 to 11 for many of the shows, and the studios are in business to make cartoons for them, not to cater to fanservice.

Many fan communities take an isolated incident and blow it out of proportion, tunring it into what's called "shipping," the romance of two characters who under normal continuity does not have one. A Billy & Mandy fan community has created a "shipping" of the two title characters, based solely on the scene from the episode "SpiderMandy" where Billy proposes marriage to Mandy. The Powerpuff community took the scene from "The Rowdyruff Boys" of the girls kissing the boys on the cheek (to obviously destroy them) and created a gazillion fan fictions of PpG/RrB romances. But those stories are more or less jimmy devices to make the Powerpuffs the author's "Mary Sue" (a character in a fan story which is a glorified personification of the author--the male counterpart is a "Marty Stu"). It's not normal canon, but the stories are written as if it were.