I'm not an achievement hunter, and I'll never get a 100% achievement rating for any game. I don't care what my final percentage is, that number, or percentage, is not a reflection on the experience I've had. I replay a lot of older games that I really love, and it's not uncommon for me to log hundreds of hours, and sometimes thousands of hours in a single game over the course of several years but I've never come close (or care) about that 100%.
But I will say that I like that feature in Steam, even though I don't care about what percentage I get. When I install a game (or reinstall), I cruise through the list of available achievements, and I'll often see a few that I'd like to get, so I will shoot for those in my play, but many others I just don't care about.
For example, in Baldur's Gate 2 EE, I wanted to complete the game without any of my companions dying:
Which is even more difficult if you encounter some of those optional quests/battles, like Kangaxxx:
I also like to get those achievements that have that glowing gold border around them, indicating that less that 10% of the players achieved them. I don't actually shoot to get those, but they're always fun to get. Like a couple from my current game, Wasteland 2 Director's Cut:
PS: By the way, a belated welcome to the PCG Forum. It's seriously the best gaming forum I've ever been a part of, where you'll never see any derogatory or mean posts. There's a bit of sarcasm floating around at times, but it's all meant good-naturedly; like joking around with a friend.