I like achievements. I don’t compare them to anybody else, they just give me a goal and personal sense of accomplishment. The Binding of Isaac: Rebirth would have been a lot less satisfying to complete if I didn’t get to see 641/641 achievements on my profile.

In 99% of games I’ve played that disable achievements with mods, there’s a way around that on PC. In the aforementioned The Binding of Isaac: Rebirth, as long as you beat the first “final” boss a single time, you can use mods freely. In Fallout 4 as you’ve mentioned… there’s a mod that re-enables achievements. So this is an irrelevant issue to me.

As far as your other question goes, I’d be more than happy to see achievements be opt-out. On Steam you can always hide your library or use SAM to get rid of them all when you’re done playing, but that’s obviously not ideal.