Yes, it's a decent question, but to say that an unactualized potential means a lack of potential is greatly inaccurate. One is not more creative without something than one is with something - regardless if that creativity actualizes in an individual case - if for no other reason than that one gains increased creative potential by having that something which the person without that something can never have.
I think the perception of "less creativity" that you disagree with is predicated on results. If you see more homogeneity in results, things feel less creative. To shift the example, take flight in combat, or the scry-buff-teleport. These options are so efficient that they easily dominate unless players make a specific effort to avoid using the most efficient thing as often as it would work (not something human beings are noted for), or unless GMs work hard to make those options undesirable for various reasons. When all potential solutions are closer together in efficiency, more are tried. When one's a standout, it tends to dominate.
Hence the perception of "less creativity": it's not really about perception, but what happened over the course of the campaign. I think there's some serious merit to both sides of the argument.
I'd really disagree with this, so much so that I think, in fact, the opposite. I think 4e design shows a deliberate increase in potential specific solutions (the spread of "spells" to all classes - coupled with reduced variables in those "spells") in order to see a reduction in the variety of innovated solutions because innovated solutions are hard to "balance" and have the appearance of favoring some classes over other classes.
To my mind, the increased importance of skills has really made it too close to call as far as the variety of innovated selections go. In practice, it is
insane the kinds of things you can simulate with a skill challenge. There's a really good example in Dungeon about how to use the skill challenge rules to run a Helm's Deep-style siege, for instance.
I also have to say that the appearance of favoring some classes over others than can't entirely be described as a misperception. I've seen groups where CoDzillas do indeed dominate, and some classes might as well not show up. The kicker is that they weren't really doing it
wrong — they were just doing it differently than I prefer to.
I think the design decision that drove the creation of rituals is the need to have classes be combat equal (although with the skinning of difference) and composed of quantum skill packets, equalized in combat, reduced to damage/condition/movement and their respective opposites healing/condition removal/movement reduction.
I think you've got it mostly down, though I have to say that class differences make them very unequal in certain aspects, more than mere skinning. Things
read very similarly, but the way that a fighter and a warden, for instance, handle in actual play is astounding. They're both defenders, but almost entirely different play experiences. There's some very cunning design in there, stuff that makes me obscenely jealous. I can't help but think equality was a major goal, but one of many, rather than
the goal.
Removing almost everything that did not map to the above 3 areas is what caused the creation of rituals, IMO. Rituals are merely the remnants of prior editions, allowing the appearance of brand continuation in the face of obvious and significant gaming differences. Rituals were than "opened" up to anyone (although not really as you must have the right feat) to compensate for a loss of immediate utility by the appearance of overall utility. ie. you can't use it quickly, but you can use it more often.
I can't agree with the "merely," because rituals add a different play dynamic. It seems vestigial if it's not quite your thing, or if you really prefer other editions' versions, but ritual magic has become another neat and interesting subsystem in its own right. Of course, I like specific genre or theme emulation in my games, and making D&D do a lot of different things, so I naturally am drawn to the strong points of rituals. They catch the sword-and-sorcery dynamic, for instance, and I don't think that's accidental.