Honestly, I have trouble seeing these "sequels" as new games. I mean Overwatch 2 was mostly a heavy balance patch, graphical patch, and pivot to F2P.
These are just large updates where they incremented a number in the name. With that in mind, this isn't a "trend", it's been going on for as long as these service-style games have existed. Fortnite's pivot from Save the World into Battle Royale, for example. Or going further back: Remember Star Wars Galaxies?
Yes, these mega-updates are often regressions... again, that's not news. The only thing "new" is realizing "oh, we should increment the number to get some hype going".