Depends on what your art is for. The problem with generic anime art for me boils down to a lack of recognisable identity. My art didn't look like my own. Generic anime art styles might be fine if your audience and themes match that. Mine don't. I don't want my art to look like it could just be somebody else's.
Doesn't mean generic anime artists are terrible. Just means that they're limiting themselves to a set of tropes and aren't exploring as many options as they could be.