Dark Souls 3 is objectively better than Dark Souls II in almost every way, so it's not the worst. It's just the least surprising. To me, it was the series feeling annualised, and proof that some of the great things from Demon's Souls and Dark Souls would just never be seen again.
It seems like world design is never going to be on par with Dark Souls again, thanks to the use of warping. There's just no need for shortcuts or interlinking worlds if you can warp everywhere. Unfortunately, that means less surprise and cohesion, and it means one of my favourite things in the original has been removed for the sake of convenience, which seems to be the antithesis of Souls design.
There also seems to be less surprising narrative moments or secrets that fundamentally alter things. We no longer have things like Dark Anor Londo, or unflooding New Londo. We no longer have things like Astraea or King Allant, where the game will forgo challenge just to unsettle you or provide lore.
The game world too is the least varied in the series too, and I found only one area truly surprised me, and even then, Bloodborne did that secret better.
Dark Souls 3 has improved the series a lot in terms of gameplay, but unfortunately, they've lost a lot as an experience. Dark Souls isn't my favourite game because it's challenging, but because of the atmosphere, the surprises, and the overall experience.
-P.S. Both Salt and Sanctuary and Momodora are very good 2D Souls-like games. If you're still hankering for Souls after Salt and Sanctuary, I highly recommend giving Momodora a shot. It goes on sale quite cheap at times.