Cause this joint, despite the dour tone, has some of the best quips of the entire MCU.

From a strictly "bars" standpoint, IW is consistent throughout, and I find myself consistently smiling.

Little things, like the way Thor references Rocket and Groot, the Iron Man interactions with Star Lord and Doctor Strange- arguably Stark-like in their own right, in certain ways, every scene with Drax...

I will say that the impossibly high stakes strike a dour tone that certainly present a harder, darker edge than any other MCU film. But I'd say the fun factor is there in droves, it's just balanced with a weightier layer than usual.