Another aspect about the encounter/daily abilities was that you could use every ability only once. That meant that even if you had found that one super exploitable always perfect power - you only had it once, and even if you had found 3 encounters and 3 dailies of that type (which probably is a real possibility after the first round of "splatbooks" was completed) - you had variability.
It is a bit of a problem for immersion, but for gameplay, it's a really strong choice. It keeps things a bit more varied. Of course, Psionics kinda "broke" that concept.
I wonder if one could have the best of both worlds. LIke, say, everyone has "maneuver points" or "mana points" that they can spend on powers, but the first use of every power is free or you get some refund or something.