Every show, no matter how dramatic, needs some humour. Take a show like "Six Feet Under", that centered around loss, death and dying yet had many moments that were truly howlingly funny. We need this to balance out the grimness because unrelenting grimness is nearly unwatchable.
I'd add the wedding dress ladies there, and totally agree they are all caricatures. I just don't find them amusing. We don't know them, we saw them only a few times and it felt as though they were just randomly (and often awkwardly) shoehorned in there for laughs, but I just found them one-dimensional irritants. It's different when, e.g., Margaret acts like a loon, because we've known her since the beginning. When she said Helen "looked like a vagabond whore" in her dress, I laughed because that's the kind of thing we expect from her. When two anonymous salespeople illogically acted like rude bitches for no reason, it just annoyed me. JMO, but people can be funny without being turned into cartoons.