This is interesting to me, because I always figured the Diablo series was prized for its moment-to-moment gameplay, rather than for its story or cinematics.
But why should I do that? I don't get that argument. I've never went back to a low level zone in any game just for the purpose of "obliterating everything". If there is a quest I missed, sure. But what's the point doing that?
Diablo 4 makes you go back and forth across zones, GTA-style. Not only for sidequests, but also the main storyline. D2 solved this by artificially constraining you to one region per act in a linear fashion.
In D4 when you pass through or go back to a zone you've been in, and the monsters are tougher, it feels awful.
AFAIK D4 does that in some capacity. There are zones that scale from 50-100 for example and if you are below 50 you'll have a bad time. It's correct that once you visit a former zone the monster scale with your level but as soon as you have the mount you don't have to put up with them. And because of the game design (a lot of dungeons, world bosses, legion events etc.) it's a welcome thing that they happen all over the zones and are not restricted to some high level area.
That has not been my experience. Yes, at certain moments, I am pressed to optimize. However, I'm currently wrecking WT3 with my necro. I know it won't last forever as I scale up, but that's fine with me, otherwise I'd have nothing to look forward to.
What about compared to PoE in the first week it came out? D4 will get better as they iterate on it based on gameplay and feedback just like they did with D3 and D2.
I'm sure they will expand on gameplay but there's no indication they'll come close to scratching the surface of PoE's depth, and I don't think they're trying to. D4 is supposed to be a simpler game with a lower barrier to entry that is more accommodating to casual players. You can't get a whole lot out of PoE as a beginner without third-party resources, there's certainly a tradeoff to its many layers of complexity.
D3 and D4 are games made for people in their 30s who grew up playing D1 and D2 and now only have a couple of hours a day to play, and that's fine