Allow me to present an analogy, just in case anyone hasn't got it already.
Chocolate is special.
If you have chocolate with every meal, it will cease to be special.
Like Sadrik, I have toyed with the idea of removing at-will powers in some manner. I find all their finicky effects to be a significant factor in battle-grind. Particularly for martial characters, but also for some of the others. Removing at-wills probably won't speed up the combat in terms of rounds, but it may speed it up in terms of real elapsed time. Less counting of when effects start and stop, and all the tiny bonuses or penalties that they inflict, more getting on with the job of actually fighting.
The way I envisioned the changes is as follows:
Melee characters (defenders and strikers): Have no at-wills. Each at-will power becomes an encounter power, and may get improved to reflect that fact. Melee characters may or may not get additional encounter powers per encounter, this is to be decided by actual playtest.
Spellcasters (wizards and warlocks): I think warlocks would remain fairly much as they are. Wizards however would have their at-wills converted to encounters, be able to use a greater number of encounter powers per battle, and be able to learn ALL spells. They would still have to choose which spells they prepared each day, but they'd go way beyond the limit of spells known that is normally imposed by 4E.
Leader/healer types: The ability to heal someone should never be tied to your ability to hit someone else. I would remove cleric at-will powers altogether and boost their ability to heal instead. Personally I'd remove warlords altogether, so I'll skip class that for this discussion.
So apart from the warlock's at wills (mainly eldritch blast), there are no at-wills in my model. While I fully realize my model is not balanced to the same degree as 4E, I feel it is much more pleasant starting point to work from. Balance from there on would be handled by how many encounter powers each class had available, or in how powerful they are.
Personally I'd also make other sweeping changes if I were to run 4E, like halving all HP. But this discussion isn't about me.
Were I in the same location as Sadrik, I'd volunteer to test his version, but I'm on the other side of the world. Nevermind.