If you watch the Christmas special of pretty much any TV show (or the Star Wars Holiday Special), they are pretty much all like this. Gunn and Pratt and the rest clearly wanted to do something similar - silly, sappy, sweet. It was something to watch with the family, have a laugh, enjoy the meta version of Kevin Bacon, hear a couple of funny songs, and get a few warm fuzzies at what Christmas means via Yondu, Star-Lord, Drax and Mantis.
It played like a pretty good parody of what most Christmas programming is. Dopey humor, a few "awwww" moments, fish out of water stuff, aliens learning about Christmas and getting all confused, a random celebrity cameo, and so on. this sort of thing has gone on for decades - Star Wars, Buck Rogers, Alf, Third Rock from the Sun, etc.
Not trying to criticize any poster here, just a general sense of Marvel, but as intricate as it was getting to Endgame, it feels like many fans are trying to force every show and film that comes out into a jigsaw puzzle, when in truth, things are just fine as stand-alone films and series and specials that don't necessarily need to all be chapters of a grand story. It's the Connected Universe, that just means there are places where they intersect. Not everything has to be a brick in the wall.