It's turned into a sketch show, though it has been for quite some time.
I think people forget that Chang was an actual person, semi normal and when he did outrageous things they stood out because he could be somewhat normal, now he barely speaks, he says nothing that isn't insane, he doesn't appear to function as a human and he's not really funny. It's the same thing too many sitcoms go through. Start off as well rounded characters, each with their own quirks, after some time the writers make them just the quirks and nothing else at which point the funny one liners become boring every liners.
Same goes for the situation they are in, they were in a fairly normal college in which some funny stuff happened, now they aren't in a college any more, it's a fun house where nothing makes sense and the stories aren't interesting.
For instance the Britta crapping herself was actually very well done, but much like an SNL skit it went on and on and on and stopped being funny. The listening to music and being weird wasn't funny, it was just being weird for the sake of being weird. The constant emergency situations in every episode is covering for the lack of funny. "normal" story lines with brilliant and funny writing was fantastic to watch in early series, particularly the first, now it's stupid story lines with cheap/easy jokes.
It also makes the truly stand out strange episodes not stand out and brilliant any more. The paintball war was brilliant, the second one wasn't as original but has a twist and made it interesting, since then the big random wars aren't special or original and not anywhere near as funny either. The multiple timelines episode was epic, but the future evil time line stuff was a joke. The multiple time lines thing was a guy imagining what might happen if the dice fell differently, the evil time line characters actually happening in a real episode(more than once) is them taking the show out of the real world entirely and it feels like it never went back. Been worse every year since the start but 1 was epic, 2 was slightly less than epic, the drop off each season since then has been painful to see.