Are levels in the endgame worth it?

I'm currently lvl 89, and xp gain is starting to slow. Are subsequent passive points worth the grind, or should I just not even bother making a concerted effort to leveling up?

After lvl 90, I wouldn't be too worried about leveling up more. Having a few extra skills points is def nice, but at that point its a drop in a bucket of your total builds power.

It becomes a bit of a grind unless you've got your builds defenses really sorted out. Sometimes I find an upgrade that improves my character enough that it can coast an extra 1-2 levels up without grinding safe maps, but reaching 100 will never be one of my goals.

After you can use lvl20 skill gems gear is far more important than levels, if you have the right gear and enjoy playing the build then you will level up a bit more anyway, but grinding to lvl100 just for the levels is no fun at all.

PoE1 is exactly the same in this regard btw. The whole reason PoE1 is/was so good is that there are so many ways to build a character to that point, that usually by the time you got to lvl90 or so you had so many ideas you wanted to try out from what you learnt building your current character, that you couldnt wait to start a new one to give them a go, that is what is missing from PoE2.