Personally, for the same reason I'd criticise the constant attempts at jokes in The Last Jedi regardless of what the rest of the scene is about: because tone is kind of important.
Like, Jar-Jar's entire character is that he's an incompetent goofball who is useless at everything he does but will occasionally accomplish things through sheer dumb luck. Also he steps in poop. And this character is present in pretty much every major scene.
I want you to imagine, let's say the Battle of Hoth. And Jar-Jar is there, being inept and tripping over himself. And as the rebel defenses are failing and their ground forces are running for their lives, we see Jar-Jar running waving his hands in the air shouting WESA GONNA DIE. Then he slips backwards on a patch of ice and drops his blaster, which fires accidentally as it lands and, idk, hits a cache of explosives and sets them off which destroys an AT-AT by causing one of the legs to buckle, or something. Another blaster shot bounces between the legs and hits multiple Stormtroopers that were climbing out of the wreckage. You get the idea. Comical ineptitude during an otherwise serious scene with supposed stakes.