true, i just think the time spent on them could have been better used on something else
That statement is generally true to all computer game related activity. By playing, we choose to do something pointless in the first place. Achievements are another option for self stated goals. There are player that play for rank, others for k/D, others for resets and some will for the achievements.
I think that completing all achievements should award you with the "Over achiever" achievement. The problem is that this achievement itself cannot be won unless you already have it.