The thrill of adding a ball, and giving yourself that extra ball security blanket is great to me, and then having more opprotunity to beat or set new high scores....
Beating a game leaves me feeling blank after a while.. its great the first couple of times, but unrewarding later on...
that was the same with my DMD games.. once i "beat" them a few times they got played a whole lot less.
AAB is an immediate satisfying repeatable goal that gives you the tools to reach an end goal. the goal of beating other people, or beating "your" best......
and that goal can forever change... to me thats what makes AAB's stay fresh forever