To me the gear grind in D2 is more rewarding than getting the exact same gear over and over hoping that the crazy RNG layers align to give you an item that’s actually an upgrade. At least in D2 once I find a given unique or am able to build a given RW, the stats have some variability, but are still what I am looking for, and can move onto the next area my character needs.
GRs “vary” but at the high end, do they really? There are builds that need density to kill and build that are more of elite hunters. Depending on what build style you’re using, you are hunting for specific map layouts that can support the density your build requires and specific mob types that can be herded (or singled out) and killed. Gets pretty repetitive as well. Then there’s bounties that gate crafting mats that are also done as quickly as possible since very few people enjoy them.
So yeah, with Bounties you technically can run through “most” areas in the overworld, including bosses, and then you have the randomly generated GRs that I spoke about above.
But in D2 you have a variety of boss runs and lvl 85 areas to farm. Plus for a lot of people PVP is the end game. Grinding out ideal PVP gear keeps a lot of people going in PVM, and then there’s the fun of the actual PvP itself. Plus there’s the DClone and Uber Trist, trading mini-game, etc.
But you’re often never really “done” until you decide you’ve leveled high enough, or have “good enough” gear, etc. Yes you can get to 99 and eventually get perfect BiS gear.
D3 I feel like “end game” could technically be starting at lvl 70, the entire character and skills progression before 70 is pointless now. SO end game actually starts when you have a full build and several hundred (thousand?) paragon and can start pushing GRs to level gems to make you stronger to push higher GRs to level gems…
Either way it’s a rat race, but I seem to find more enjoyment with D2.
That said I wouldn’t be opposed to adding some “end game” runs in D2, either by taking a few less commonly used areas and bumping them up to lvl 85, or possibly some sort of map system as long as it was well done, balanced with existing areas, and not a GR copy paste. The OG D2 Devs actually experimented with maps some in the Mythos beta once upon a time.