Ok, here's an important thing about 4e that I would suggest that even die hard fans of other editions consider: it's foundation is excellent. In my opinion, it's a better foundation than any previous edition of D&D, though I leave that comparison up to the reader. But what does that mean?
I mean that if you took some characters and stripped them of classes, powers and almost everything else, you have a very solid little set of skirmish rules that strike a very strong balance between speed and depth. Boiled down to that level, it's easy to see that there are just a handful of refinements from 3e, and the line from the original dungeon skirmishing is very easy to see.
I've steadily come to realize that the thing that keeps drawing me back to 4e is the simple power of that foundation. You could build entirely different games on top of it which could be entirely awesome. Different stats? Different classes? No classes? No Powers? Totally different power models? it would be easy to build such a thing on top of that chassis to capture almost any flavor or style of play that you want.
See, that's the thing about the classes and powers as they exist: they represent a decision about how the game should look and feel. This is not a bad thing - the designer's vision is a large part of the reason you buy a published game - but because this look and feel is so striking, it creates a sense that it's the foundation. That is, it's easy to look at 4e and think that if you want to change it, you should change powers and classes. 4e makes it feel like those are low-level changes while they're actually quite high-level.
I don't think this is good or bad in and of itself, but it mingles interestingly with the other realities surrounding 4e, specifically it's semi-openness (which encourages high level tinkering) and it's model of game-as-web-service (which discourages many types of tinkering). Altogether, it reveals my frustration - I want to take that foundation out and play with it. Doing so is how you can get awesome things like the (very much not open content) awesome of Gamma World.
But that's not an option, at least not for anything public. I suppose it might be possible to build it forward from pathfinder or to create something similar from scratch, but both of those feel like inelegant solutions. But I want to find a solution, and I can tell you why:
I want the game I can _make_ with 4e.
Stop for a moment and consider what happens when you start looking at all those powers in 4e as building blocks for a simpler game. If you're starting from scratch, unbound by what's at-will, encounter or daily, then you can build almost anything using these parts and a little duck tape. Like spell points and spell lists? Make a list out of a set of thematically similar powers, and give them mana costs. Don't like encounter and dailies for non-magical characters? Adopt a system where lower level encounter powers become higher level at-wills. Want to make power sources more important? Maybe come up with new ways to recharge dailies? It all opens up.
Obviously, I can already do this at home, but I'm a social guy. I like sharing. And that - the game I can make with the 4e parts - is the game I wish I could be sharing.