Its not D2, or D3, both endgames are trash gameplay combat wise.
Exactly. Absolutely ALL aprgs that exist has terrible trash-boring-unchallenging endgame gameplay in all those areas where you feel overpowered. For this reason there must always be some places where this is not the case and that will be very rewarding for you as a player. On the other hand, those easy places should not be effective for farm anymore. Like, if you want overpowered trash gameplay (just to relax), you can do this, and you will get some reward. But it shouldn’t be even comparable to that reward that hard area gives. I don’t see any other possible way to rectify the situation.