They showed the game at 30fps, same as Ratchet, because graphics sell more than framerate. So they have sell to you the game by graphics, but will you buy it because of framerate? Now people imagine playing that gameplay they saw but at 60fps, but reality is they will play a downgraded version of that video they are praising but at 60fps. Just like Miles Morales, Valhalla, etc. At 30fps they look as intended. At 60fps they are PS4 games but smoother.
I'm tired of reading people saying next gen graphics are not so impressive just after saying they play at performance mode. Of course the jump in quality will be minor if we add 30fps more to the jump. Half of the extra power new consoles have is spent in achieve higher resolution and framerate. Resolution can be tricked by upscaling, but how we trick 60fps?
Cross gen and mandatory 60fps modes is like having a PS4 pro called PS5.