people are mean because, a, people are assholes, and b, manga fans are sick of wannabe "manga-ka" who aren't even Japanese trying to foist cliche crap on them that they obviously spent the most effort on trying to make it look "Japanese" or "manga-like" and thus didn't put nearly enough effort into the plot, characters, or creating their own art style. there's also comic fans who are sick of the "manga kiddies" acting as if comics aren't good enough for them when some comics are actually superior to some manga.
you want to step on the least amount of toes and get fewer disparaging remarks? say you want to create manga-inspired comics. some will still b***h, but there'll always be someone doing that, but you'll get less bitching overall.