Daily powers are both about the game, getting the hit/miss/effect--and about pacing, when the player controls the narrative flow by pulling out a slick, effective move. Making them reliable (or some of them reliable), affects both things. It tampers with the game side with questionable results, though some of the variants above effectively address those issues. It tampers with the narrative side by saying that, essentially, every day the character can not only try each fancy move, but eventually pull it off. This is a little too pat for me, even like player narrative control as much as I do.
To make daily powers whiff marginally less on average, but still preserve existing game and narrative balance, what I'd do instead is something like this: Each time you miss with a daily power, you get a +2 bonus to future daily attempts. This stacks. As soon as you hit with a daily power, it resets. Or, if you don't mind the extra book keeping, as soon as you hit with a daily power, it goes down by 2. This counter does not otherwise reset, ever.
I prefer the simpler option of complete reset on a hit, because the moving counter (lower by 2 on a hit) somewhat marginalizes parties that work hard for teamwork bonuses. However, this is largely a question of what you want at the table.
And of course, once you've gone to the trouble that I've outlined above, you can probably do something a bit similar but easier to track by being a trifle more generous with action points, and allowing APs to restore a missed, no effect daily.
