3rd versions are the definitive versions of the first two games, which people didn't mind paying for since they had enough new content to justify buying it again, i.e a Battle Frontier, redone storyline, general QOL changes, ect.
B2W2 is the best example since it has a metric fuckton of content and is the standard most fans hold 3rd versions to.
People are pissed about USUM because it's not meeting the standard set by B2W2, but it goes even further than that and has very little new content overall.
