I LOVE The Hobbit trilogy. I know a lot of people don’t, usually because they’ve been familiar with the relatively short book for years (or decades) and it would be understandably jarring to see it in the form of a trilogy of three long films.
But, I hadn’t read the book yet myself at the time, nor did I really know much about the story outside of the few details The Lord of the Rings movies referenced. So as the movies came out, I just soaked up every minute of them. They definitely aren’t as great as TLotR trilogy, but it didn’t have to be. I think they’re wonderfully fun and an absolute delight. I look forward to upgrading to the 4K discs.
The Hobbit is a weird style movie. Whereas the book was written as a light Childrens story (for the time, not for now), but so much of it was introduction to Middle Earth -- what's a hobbit, what's a troll, wizards, multiple variety of elves, dwarves, intelligent noble animals, dangerous corners, types of magic, and a Dragon most all which have to be explained sometimes with humorous vignettes.
With LOTR already in existence as the Known World it wasn't needed to be as an Introductory movie and without that, there's mostly 45 minutes of story left (The Rankin Bass animation) and they'd have to dumb down (or maybe Innocence-tize would be better) the world that we already know is deadly serious. If the Hobbit had been made as a movie 1st they likely could have kept it more innocent/simple/charming and let LOTR become the dangerous world -- like the books did and the Harry Potter series did. Going backward might work, but I suspect there would have been a backlash of "that's stupid, why'd he do that" since the what comes next is already known.
Melding Hobbit basics with Silmarillion stories (or some made up stuff) I guess they felt would keep the tone of the films much more in line with the world the movie fans (not the book fans) already knew.