Allow me to clarify: having an encounter or daily power changes your behavior on a round by round basis by giving you a limited resource that allows you to impact the encounter in a significant way. The decision of whether or not to use that resource this turn is a significant effect on gameplay, as is the effect it has when you do choose to use it. Having one thing you can do three times per day? Yes, that does affect your round by round behavior a bit, but not that much. Certainly not compared to having four different abilities you can use once per day each and four different abilities you can use once per encounter each, all of which have different effects on the encounter beyond just changing the numbers.