Even the original Baldurs Gate games had plenty of silly humour, that broke the 4th wall or poked fun at the game itself. Especially 1 had silly encounters hidden here and there on the world map. I think a main thing with why it feels strange is that it happens so much. If every other encounter is a Monty Python sketch it loses its charm quickly and makes it harder to immerse, where if it is a rare thing that happens now and then makes for a fun tongue in cheek moment. It is like all humour basically: timing is important. And balancing it with the serious parts. It might make it feel more like finding a fun easter egg (perhaps one of many) rather than feeling like you are basically in a Monty Python movie.
It fits DnD (I mean, tabletop games have plenty of it) but I think what people mind is that it becomes "too much of a good thing" in essence and it is forced on you rather than be a fun intermission within a serious story.