Thats because SquareEnix are so awful at marketing.
A game like Final Fantasy XVI could make a lot of money if they:
-Released it day 1 on PC, fully optimized and polished
-Did proper marketing with build up prior to its release, showing gameplay, releasing trailers and creating hype
You can't just stealth release a game 1 day later with no actual hype or build up and expect people to care, if im not wrong they also chose a date where another big game was released.
I hope Square takes a long, hard look at BG3. Universally loved GOTY that made a shitload of money, while staying true to the series' roots and feeling modern at the same time.
Square instead thinks it was a good idea to make everyone mash the X button and watch the screen fill with particle effects while Clive does somersaults. I tapped out on FF after FFXV and FF7R.
Do you think that if Final Fantasy goes back to turn-based it will magically be more successful and make more money?
I honestly doubt it, i think their problem isn't being turnbased or action, its about proper marketing first and actual quality second.
If a game of Rebirth caliber were to release Day 1 on Steam, with proper marketing i'm nearly 100% sure it will have great numbers, they have all ingredients for success.
-Open World
-Action based so its more flashy
-Iconic cast of characters and has a legacy name behind it
-High quality all over the place
-Visually looks great
All they need to do is market it well and have it optimized for PC, then easy money printing.