I agree. When I go for additional content, I do it after I finished the story or if that's not possible during relaxed parts of the story without any urgency. Need to catch the bad guy because he did something bad and he's on the run? Do it right now! Meet in the next City to talk? That stuff can wait for a bit. For me personally story goes almost always first.

I can 100% say that going full completionist will ironically make you lose out on other experiences. Imagine the game having a great story and you love it. Now you see this sidewalk alley in the game but you know you must save someone from whoever. Do you follow the false sense of urgency, manifesting the feeling the devs wanted you to have, or do you downplay the entire part by ignoring the story for some time? If you follow the story, you're engaged, characters matter to you personally and it all feels important. If you go into that sidewalk alley, read some newspapers in the search for Easter eggs and find a funny text when searching a bin that might be funny, but it trivializes the story. It's your choice. What do you choose? Neither of the choices are bad of course, I just wanted to point out how losing out on content can be a positive experience.

But achievements are optional? It seems like you noticed a problem in your behavior which kills your enjoyment. Instead of wanting other people to fix your personal problem try to work on yourself. If you know that's a bad trait and you're having less fun, then force yourself to NOT finish that part 100%. Don't wanna get the minor upgrade because you don't feel like it? Don't do it.