I want to start by saying that any criticism that isn't aimed specifically at the character in question is not productive in any way, regardless if it's intended as basing or not. Character threads are not discussions about evaluating creators.
Barring the extreme (offensive/obscene material), I personally feel that there's never a good reason to rip on anyone's work, at least not on a character thread. That's what general mugen discussions exist for and even then, there's a tactful way to go about it but I digress. All that does is invite unnecessary negativity, hostility, and off-topic dialogue that often has egocentric motives. This is a hobby above all else, and I don't support anything that intends to demotivate people from creating, no matter how horrid the quality of work might be.
Seeing that I'm certain that a Chuchoryu char release partly inspired these discussions (figures), it's evident that his works are pretty polarizing. And I found that both threads that I know of (here and MFG, my more active place), the show started with people making comments about CCR's history rather than the character in question. Not going to ramble too much about it, but a lot of trouble would be saved if people would stop feeling compelled to say what they believe in his char threads. If the character sucks and you feel he's not going to improve it or acknowledge your feedback, ignore the thread. This goes for any character or creator.
To summarize, feedback stops being such when attention is taken away from the character. Though of course there's more leniency when the off-topic speak is positive or consists of friendly banter, which is fine.