All this song and dance is lovely to see and hear, but it still ignores the point.
Balance is achieved by eliminating unforseen synergies. Creativity is the finding and utilization of unforseen synergies. Either 4e is more balanced than previous editions, and therefore limits unforseen synergies (and creativity, perforce) more, or it is not better balanced, and does not create said limitations.
You cannot have it both ways.
(Where the balance/creativity fulcrum should lie is another question; one which relies very much on subjective taste. Denying that there is a tradeoff between the two, though, is irrational.)
RC
I don't think you're wrong, but I don't think you've considered the entire picture either.
I think the tradeoff can also be between balance and the degree to which the system rewards creativity.
Imagine that the DM describes a boulder strewn hill topped with trees. As an ogre (a very tough and dangerous enemy) approaches that hillside, one of the players decides he wants to grab a tree branch and use it as a lever to pry free a boulder, sending it tumbling down onto the ogre.
System A isn't much concerned with balance, and therefore with successful resolution of the check to pry the boulder free, the DM decides that the boulder crushes the ogre, who is killed instantly.
System B, however, is very strict about balance. Based on the player's level the rules state that improvised damage effects shouldn't deal more than X damage, although they may also knock the target prone if it fails it's resistance check. Upon successful resolution, the boulder rolls down and hits the ogre for X damage, possibly also knocking him prone.
Both systems allow the player equal freedom to creatively exploit the area around him (which the DM merely intended as window dressing). The difference lies in how the action is rewarded. System A offers the potential of very large rewards which undoubtedly appeals to the creativity of players. System B limits the size of those rewards, ostensibly for a better or more challenging play experience. System A allowed the player to neutralize the challenge in it's entirety, whereas B gave the player a "bonus" to the challenge (shifting the odds of the ensuing combat in his favor).
I think you're mistaken in saying that you cannot have it both ways, because (IMO) there's a third factor (reward) that you haven't accounted for. The potential exists to have both balance and the potential for creativity, so long as you are willing to limit the fruits that may be reaped from that creativity. Even the Wish spell had limits as to what it could accomplish, presumably for the sake of balance.