Decline happens in your heads. I remember very similar talk about mainstream and dumbing down about games that regarded as classic today. This is set of biases talking and you don't want to analyze it. You're doing the same thing that rockers did when they heard that thoughtless loud heavy metal; most people who witnessed birth of rock; most people who witnessed birth of rock; most people who witnessed birth of impressionism; most people who witnessed birth painting pictures other than icons in the churches and so on. They too had arguments that looked valid to them and didn't seem like arguments at all from the outside.
Did you seriously just compare crappy commercial RPGs to Monet??? So EA is Renoir, Activision is Matisse, Bethesda is Cezanne? My grandmother was a professional sculptor and she’s rolling over in her grave.
Let me explain why you’re wrong using one example: Gustáv Klimt, the second or third best painter of the Austrian expressionist school. Klimt painted gorgeous pictures that were very much ahead of their time. His works were popularly despised but loved by the avant-garde.
Feast your eyes on Judith und Holofernes (that’s the severed head of Holofernes in the lower right corner).
He was painting masterpieces, but he couldn’t make a living out of it. So Klimt decided to go into a different line of business: doing set design for elaborate parties thrown by the Viennese aristocracy. Basically just boring scenery. And he made a killing, because aristocrats would pay lots of money for a famous fancypants artist to paint their cardboard trees. But his sets didn’t have any particular artistic merit because they weren’t supposed to—if he’d tried to paint something good he would’ve lost his job.
What does this have to do with RPG development? Klimt’s paintings are what the best games were like back in the genre’s heyday. Klimt’s crappy party backgrounds for rich people are what pass for big budget RPGs today, the Bethesda and BioWare junk with little merit that nevertheless makes these studios a fortune. With the benefit of a century of hindsight, no one believes Klimt’s later commercial work is better than his real art. Like Klimt, BioWare literally sold out and they haven’t made a halfway decent RPG ever since.
TL;DR... The tension here is not old vs new, it’s true greatness vs the commercial impulse, a story that’s as old as civilization. We’re not too set in our ways to appreciate a brilliant new art form, we simply have taste enough to know what’s good and what’s not. If someone wants to shake up the conventions of the genre (I’m looking at you No Truce with the Furies, which, by the way, would’ve been a great title for an expressionist painting) I look forward to it with tremendous enthusiasm.
To paraphrase Alexander Hamilton, the masses are the asses. It’s very rare for any kind of creative work to be both popular and excellent, and in the few cases where the stars align, a great book or movie or game that does achieve immense commercial success is almost never popular for the right reasons.