The thing is that he wasn't really giving criticism, it was more flaming. Comments don't have to be always positive, but "Oh my god, really? The same armours again? Your works are boring, every are similar." just isn't a useful comment.
Also the way how he responded on this wasn't exactly friendly and appropriate and only later he explained what he ment, still in an unnecessary negative way.
It's understandable that it's not motivating for someone who is new to continue posting when getting unnecessary negative comments that are missing clear suggestions of what to improve.
So therefore my suggestion, if he wants to see other kind of sprites he can also just ask or suggest this in a normal friendly direct way since all the bash around it was just unnecessary.