Every gen it's like this now.
PS4 was PS3.5, there was no need for a next gen in 2013!
Now PS4 is fine, PS5 isn't impressive, no need for next gen!
Then let's wait for the PS6, when the PS5 will be fine and there won't be no need for it.
Just look at TLoU and TLoU2 and you'll know what kind of quality jump to expect on next gen, then add to it.
Next gen will sure be exciting.
I think there's a degree of diminishing returns.
Compare DKC3, arguably the best looking SNES game
to Crash Bandicoot, an early PS1 title
Take DK64 which I'd say was arguably the best looking game of the PS1/N64 generation
and compare it to Sonic Adventure, a launch title on that gen's weakest system
I think there's a notable difference.
If we compare images from Snake Eater
To Perfect Dark Zero, a launch title on the XBox 360
The difference gets smaller, but still is very noticeable (especially because of the resolution bump).
Going from GTA V on the 360
To Killzone Shadow Fall on the PS4...
The difference is smaller imo.
And from Ghosts of Tsushima
Difference is smaller still.
Obviously there are limitations to comparing screenshots from individual titles. Different compression genres, etc. (and tbh I did check to make sure screenshots were on the original hardware, but things get mislabled on the net), but I think if you compare the best looking games from the end of one generation to the best looking launch titles of the next, the gap is getting consistently smaller. And especially because this time around we had mid gen boosts to the consoles, the gap shrinks further. Whether or not that's enough to excite is an individual thing. For me though, not really.