From the perspective of game balancing and ease of play through combat situations, that's fantastic. From the perspective of roleplaying through the game mechanics, it's ruinous. Putting each class's abilities 'on rails' like that immediately excludes the possibility of any character ideas that don't fit within the confines of the paradigm.
Say you want to be a Shifter. You want to be a druid who's never in his natural form, but always flying as a bird, sneaking as a goblin, fighting as a griffin. How's he going to fit into 4E? Well, let's see what he can do.
At-Will Abilities:
Bear Claw: Attack vs. AC, 1d8+1 slashing damage as you grow bear claws and attack. Rar!
Per-Encounter Abilities:
Cheetah Speed: You move an extra 3 squares until the beginning of your next round. Zoom!
Per-Day Abilities:
Lion's Might: You turn into a lion for 2 rounds. This gives you +4 strength. Roar!
Um. Kay. But where's the flying as a bird, sneaking as a goblin, or fighting as a griffin? Those things don't really fit into a per-encounter setup, they're nebulous things that last for hours (traveling as a bird), take place outside of fights (sneaking as a goblin), or just aren't included in the designer's list of what the class should have in its abilities (griffins). If you don't feel that your Shifter wants to have bear claws, or run faster, or boost its strength, tough. In order to fit into the 'game first, roleplaying last' model, each class needs to have clearly-defined abilities that are carefully balanced so as not to make the other players unhappy, so you can't have anything so freeform as a blank check to turn into random monsters. Now your character concept sucks, shut up and reroll a wizard and cast Magic Missile every round for your 2d4 damage.