you cant really compare shotacon to yaoi since yaoi is two men who are both of a consenting age (generally) while shotacon is specifically where at least one of two people in a relationship are underage. not the same thing.
i do agree that people cant just say shotacon is bad when #1 its fiction not really good or bad just a type of preference. #2 the people saying it really have no say in the matter, if you dont like it dont read it.
i neither condone nor judge shotacon and its fanbase, as i previously said - its fiction - aimed at a particular target audience for the sake of entertainment and profit.

if shotacon is so bad, than the same can be said to yaoi right?
if you hate shotacon so much than don't bother to comment. not all people hate it. every person has their own view