It might feel better if you have to complete those achievements within limited time (it can be a long time, but still a clear limit)
Perhaps, you also need to survive until that limit, even after completing the necessary achievements.
So you have to do some time management as well. Maybe you can get all the achievements by going all in, but expend too much resources doing it and fall before the time limit. Or maybe you want to play it safe and leave a difficult achievement toward the end (eg build something big which requires selling most of your army), but something unexpected slows you down and you lose.