No-one is stopping people from playing 4e creatively. No-one. I loved it in our 4e campaign when a players sealed a cave entrance by using muscle to move rock over the entrance (athletic test) then using Ice Storm to seal it. Yay! Go Players!
But here is the thing, I haven't read one post that sais 3e, or 2e or 1e stifles creativity. Yet this issue comes up again and again and again for 4e. Now you can spend your time saying "Its the DM's fault for not allowing creativity" or "Its the players fault for not being creative" or "There is nothing stopping you from being creative in 4e" (because there isnt) but the fact remains that this keeps coming up.
If this was a marketing company, they would be asking why this phenomena was occurring, not blaming customers for "playing it wrong". When Coke came up with clear-Coke and it failed misserably, did they spend their time blaming the customer base, or did they very quickly review and re-jig clear-coke out of their product offering? To sit there and blame player and DM's for not being creative is just not how anyone should be addressing this.
Surely, based on this coming up time and again, we can at least acknowledge that there was something (or a number of things) 4e did which dissuaded at least a sub-set of players from X-dimensional problem solving and power interpretation.
Well, I'm not sure that you can't find threads that talk about 3e stifling creativity. I'm actually pretty sure that you can. But, your point is well taken.
And, really, I don't think you have to look any further than the first three core books for 4e. The PHB, DMG, and MM are written in a style that presents the game in a very, very specific way. From some rather unfortunate word choices for examples (Skip over meeting the guards and get to the good stuff ... like combat!) and the whole presentation of the PBH, you get a game that, on paper at least, looks very rigid.
Sure, there's a crap ton of stuff that you can be creative with in 4e. But, it's buried under the mountain of crap that is presented as
a fait accomplis. Rituals! Fantastically creative ruleset. Buried at the back of the book, barely supported and pretty much the red headed stepchild of the book.
Someone opening the 4e PHB is going to see classes described by their in-combat role (Role is the very first thing listed after the class name), most of the powers are presented as what you do in combat and anything that is not centered on fairly rigidly presented combat elements is relagated to the status of footnotes, either presented in the front introduction chapters (does anyone actually read these?) or in the back, in the very last chapter after a section that is about twice as long - Combat.
I still maintain that the biggest single issue with 4e wasn't really the mechanics (although I get that these are issues as well, certainly. I'm not trying to sweep away the criticisms) but rather how the game was presented. It LOOKS like a gigantic combat board game.
So, it's not a wonder to see that people have this interpretation of the game.