Why can't devs deliver a "Next gen" graphics moment with PS5/XSX?

[bdbdbd]

It's expensive to make good looking graphics and optimise them on the hardware. Especially when making "twice as good graphics" requires to "ten times more power", while the difference is visible when the graphics are four times as good. Also, as many of the games are made PC in mind, the games do not focus on making the best looking games at 60Hz, but actually making the best looking games at 300Hz, so what's actually limiting many of the games is increased frame rates from what we had 10-15 years ago.