Honestly, I have yet to see anything that 4E does well that you couldn't do equally well in previous editions. If you're looking for an out-of-the-box default of "this entire campaign will be played at the mid-level power range from previous editions", 4E gives that to you. But doing that in previous editions required about 10 seconds of house ruling ("roll up 6th level characters and I'll be awarding 1/10th the normal XP"), and that still gave you a wider range of supported play styles.
I disagree. Seriously, even taking your suggestion at face value - playing a balanced game at 6th level indefinitely clearly can't compare to playing a balanced game over 30 levels of character advancement.
I'm not sure what you think 4E fans like, but an unchanging 6th level game isn't it - it is the benefit of having an entertaining and balanced game that still lets us play average heroes who eventually become epic movers and shakers. Or a game where we can focus on our character concepts without worrying about that crippling our characters in combat. Or a game where we can try out crazy things in combat without the DM needing to stop the game for half an hour and consult rulebooks.
Now, I'm not saying earlier editions couldn't potentially offer all this, or that 4E alone is able to present these things. But these are all elements that 4E offers and many fans enjoy, and I think your view of the game seems to completely disregard them.
One of the reasons 3E continues to get played at our tables is that our circle of gamers isn't unified in its taste: Previous editions of D&D weren't a one-size-fits-all solution, and were thus capable of catering to a wider and more diverse audience.
Similarly, I've seen 4E games played purely hack-and-slash, and 4E games focused on roleplaying and intrigue. I've sat down at LFR tables where people just wanted to show off their cool powers, tables where they wanted to experience the next part of the regional story-arc, and tables where people spent half the session cracking jokes and playing word-games with faeries in the woods.
The LFR examples are particularly compelling for me, since I recall how I saw a lot of people driven
away from Living Greyhawk as it grew more and more focused on just being about the challenge and the power-game. Now, that was admittedly not just due to the 3rd Edition rules, but also the design of LG itself - but the fact remains that WotC tried to learn from their previous mistakes in their presentation of LFR. And in my personal experience, they have definitely succeeded in presenting an environment that welcomes a lot of different types of gamers in a way that LG had trouble with.
In any case, I think every edition has been able to be played in a variety of ways. I don't think 4E is any different. I don't even think the goal of 4E is to be any one thing, and there are certainly plenty of elements in the rules - and plenty of advice in the DMG (and DMG2) - that seems specifically designed to allow for multiple styles of play.