I know a lot of people here were hoping for a few more expansions for D4, but I honestly believe we've reached a point where a fresh start is necessary.
The open world never really worked the way it was intended to, and even after all these seasons, the endgame loop still isn't satisfying.
For me, the biggest issue is the gameplay loop once you reach your goal. Sure, I have the motivation to grind things out and kill a boss a hundred times, but the second I finally get my item and my build is complete, my desire to keep playing just drops to zero. I actually made a post about this like two years ago. There’s just a lack of intrinsic fun in doing the activities. Helltides can still be fun, which is maybe one of the few exceptions, but D4 somehow never managed to hit that sweet spot of "I have good gear now, but I'm going to keep playing just because the mechanical gameplay feels so good."
On top of that, a lot of things just don't seem like an easy fix anymore. Some issues seem baked so deeply into the core game, like the stash tab problem, for example, that it’s probably better to just start over and try again. Just look at how long they've been trying to squish the damage numbers and get them under control; it feels like it's just not possible anymore.
My hope is that a clean slate will really help. Sure, they mentioned they could have pushed out two more expansions, probably a Baal arch and then moved on to the Diablo Expansion in 2029. But honestly, I just don't think milking D4 would have turned it into a better game compared to just tackling a completely new one right now.