Most Gameboy Advance Games are dumb. Sure, they're portable, but they only entertain you so far. Plus, batteries last only so long, too.
I'd like to point out I've put over 150 hours on both Pokemon Red and Ruby versions, and then all my tactical games I've probably put in atleast half that amount of time. SO as to how long they last, it could just be you haven't played any good ones, I suggest you check any of the games Gar listed.
Also about Batteries: They made GBA player and the rechargable SP for a reason.