This has always been my problem with these limitless games. In a normal cRPG my hour is normally spent talking to NPCs, getting involved in the plot, going out and killing a few monsters in interesting battles using a plethora of newly found/learned attack items and varying tactics, getting excited about a decent loot drop, going back to a merchant, fiddling with inventory and being motivated to push forward to experience lots of newness in plot, environments, tools, tactics and NPCs. The whole hour will require my mind to be fully occupied by a whole host of varied continuous thoughts about what just happened, what I can do to improve my state and what's going to happen.
It might, on paper, seem like the sandboxy games offer something similar, but whenever I play them this never seems to be the case. The loot is mostly uninteresting, the environments take hours upon hours to change, the NPCs never seem varied, the battle tactics are always just shoot things in the head with little variety and wielding a twelve bore instead of a pistol just doesn't fill me with the same joy has replacing a regular sword with a sword +1 plus fire damage. Upgrading a helmet to another helmet with slightly better stats just doesn't feel the same as replacing a normal helmet with a Crown of Thorns with unusual bonuses. My brain just has nothing to think about beyond reacting to jump-scare bad-guy drops while turning myself around in an impossible maze.
But when I empathise with someone who likes repetitive drudgery and doesn't get bored by this sort of thing, then it all makes sense. It's just a wonderful alternative world for people to escape into… for as long as possible, like walking into the holodeck. And I don't think comparisons can be made between such divergent game styles, comparisons can only really be made from a like-to-like perspective. So since I never play games like this then I can't comment on the true nature of it's quality, but I can reiterate that there's no point whatsoever comparing F4 (or any game like it) to any isometric cRPG, and doing so would be the most futile thing possible. As I said, give these kind of games their own category for heaven's sake.