Ultimately, it's no surprise that the Systar System denizens aren't really the bad guys. If a movie in 2019 came out with the regressive statement that "little sisters suck," that would take us back a few years in kid's entertainment. Bianca's just trying to get her brother to play with her, and stop a war that would lead to an armageddon ("our-mom-ageddon") that would cause parental interference. The pop music isn't bad! It's fun! The glitter isn't nefarious! It's just glitter!
The real bad guy is Rex, who is actually Emmet from the future. In his timeline, he was slighted by the Systar System crew, and went back in time to enact his revenge. He's what happens if men grow consumed by what some ideal of manhood is supposed to look like. He's a warning to Finn that he should be nice to his sister or he'll turn out a woman-hating jerk. And, yes, he's a vision of present-day Chris Pratt.
A star sending up his own image is nothing new, but a star casting his current public persona as an unequivocal villain representative of a larger social ill is a more curious phenomenon. It feels like sly -- or maybe not so sly -- work on behalf of Lord and Miller, recognizing that their star maybe hasn't changed for the better. The message of The Lego Movie 2 might as well be: "You don't have to be a dinosaur man who negs women to be cool."
But even so, Rex drags down the rest of the movie. Especially before the reveal that he's the bad guy, the scenes between him and Emmet lack the spark that the scenes in the Systar System have. Perhaps it's just that Rex's whole deal -- and in turn, Pratt's -- isn't all that compelling. The Lego Movie 2 undercuts it with glee, but that's predicated on the idea anyone finds him interesting. But, hey, at least there's a fabulous end credits song, featuring Beck, Robyn, and The Lonely Island.