Wasp started out as airheaded comedic relief and never really improved. There were attempts to make her "competent" but no real character growth on her part - after she left Pym (because of things Pym did) she just started ordering around the Avengers, without anyone bothering to show us any kind of mental transition. So the attempt to make her "competent" never stuck, because it wasn't done naturally, and she kept vacillating between being a generic "competent" heroine and "lol, she's rich and shallow" comedic relief. As Gail Simone put it, when Black Canary and Wonder Woman were first introduced, they were girls that could kick ass. When Wasp was first introduced she was there for "oh no, fighting has mussed my hair" jokes. She wasn't just a character I dislike, I could forgive that. We can't all see eye to eye, there are lots of characters that I don't like, but I'd feel sympathy for their fans if they were killed.
But Janet's position makes her something different altogether. She was a founding Avenger, the only woman among them. She'd been around since day one. She was the woman almost always on the team, the face of the female Avengers, had been for decades, and hon, that was not a flattering face. She was making female heroes in general look bad. When you're out there representing women for Marvel's biggest (non-X) team, you get held to unique standards. And by those standards Wasp gets a big fat red F.