Yes, I agree that there are more simplified games today than ever before. But the same is true for deep, detailed games. There are simply way more games AAA, Indie, and free/open-source. Ever heard of Dwarf Fortress, CataclysmDDA, or Skyrim (yes even AAA titles)? There are many games with more depth and details a single person can handle in a lifetime, look around. And if GTA doesn't offer more flight simulator than any of the 90s games, I don't know how you evaluate flight simulators. If it is the details in physics and control have a look at Kerbal Space Program (never played it, never was a fan of flight sims, sorry). If you want simulators in general have a look at Truck Simulator. There is even a harvester simulator but that might only exist in German, not sure.

I bet if you look around hard enough you might even find an open source implementation of your favourite flight simulator with better graphics. Wish you the best luck in finding one. :-)