I think what we all need to appreciate here is Disney under Eisner was bound on making cheap DTV sequels to all their movies, even going so far as crushing a bunch of episodes of an unsold show together to make a "movie" out of them. Toy Story 2 was exactly that case, but Pixar wanted to do something bigger and bolder and it actually gave them a theatrical release. It was their third movie, in fact. It was made out of pressure by Disney, but they managed to make it into something more.
Side note about the Disney cheapquels, the one that would have actually been great, a Hercules sequel based on one of the original treatments, was never made.
As for franchise films, it isn't just so much about how they make more money than stand alones so much as they're planned incredibly in advance. Everyone's trying to start something similar to the MCU, but without the varied concepts and genres that make them actually good. As for Pixar, while I'm sure there's pressure internally to make follow up films for franchise and merchandising sake, I can't help get the feeling they've gotten burned on some of their stand-a-lone concepts lately.
Remember Newt? They had this great concept about two newts having to develop a relationship they didn't want to get into, and then the overrated Rio and the completely unnecessary Alpha and Omega were fast tracked and they had to abandon the film completely. Then after announcing a Dia de los Muertos film, Book of Life came out. Though, to be fair, Book of Life was a film the creator was trying to get made for years, probably even before Pixar announced it. Not to mention Brave and Good Dinosaur hit multiple stumbling blocks in production (in the case of TGD, it actually bettered the movie). Plus, other than Toy Story and Cars, the sequels to Pixar films aren't exactly released a couple years later. Dory is 13 years after the first one? Incredibles 2 as well. A far cry from TS1 being followed by TS2 in a matter of 4 years. I mean, I can't blame them for going with established characters, but it seems these aren't exactly as quick and thrown together as most. Incredibles 2 was a possibility for years, but that was up to Brad Bird finding a strong enough concept.