Calling FFXIV a mainline FF game is honestly a tad laughable. It's a spinoff in a different genre that they slapped a number on to draw people in. It'd be like expecting a new Half-Life game and getting Fortnite. And trying to pretend that FFXV wasn't in development for more than ten years because it got a name change and some team shakeups part way through is a tad disingenuous.

Also, the FFXIII sequels were slapdash sequels to a slapdash game. FFXIII didn't even have a clear direction until about 18-24 months before release, it was remarkably half-assed and poorly made, and instead of developing newer better games they released a couple of quick sequels to take advantage of the fact that at least they'd already built an engine, didn't have to think too hard about writing the world since the foundation was already set, and they could cannibalize as many assets as they wanted to make life easier. So yeah, sequels slapped together in short order to make more money on a game that was slapped together in under two years because as usual Squenix sat on their asses with no direction and accomplishing nothing for years before they realized people expected them to actually make a game out of it. I'm also not particularly impressed that they can have all of these separate teams working on all of these separate games and it still takes them at least twice as long to make a game as anyone else can get it done.