The current system is good for team play and it is also good for solo play as long as the player isn't in a rush to get to the top.
I respect your opinion, but there is a big flaw in it.
The entire point of the game is to "get to the top," where "top" means "I can be safe from zombies and not die." That is what drives the perception of
progression in a game without a storyline.
The alternative is to view death in-game as trivial, in which case there's no sense of threat, and no urge for any kind of progression at all. You might as well be playing the original Doom, and 7D2D is not supposed to be that kind of game.
So, you can't criticize players for "power leveling" when leveling is pretty much the entire point. They're playing the game the way it's meant to be played.
That said: I agree with you 100% about the new attributes/perks system, and the lack of level gating. It does give players more choice, and that's a good thing. They'll still be "power leveling" but they'll be able to power level their way.
My current issue is that it's nearly impossible to level simply by mining or crafting. But that's a balance issue that TFP are already aware of, and working on, so I have faith it will be better by the time stable hits.
EDIT: Actually I still do have an issue, which is - what do you do once you do what the game is driving you to do, and "get to the top?" It's like you've won the game but are still playing it.
I don't have any solution to that, though, without fundamentally changing the nature of the game itself. So that's more of a philosophical question than a critique.