Yeah, the problem is really not power but trying to fit the power in the same sized box. It used to be that console makers just add transistors to make the machine more powerful but we're reaching the end of how many transistors can be put in a box the size of Xbox 360. Unless consumers don't mind larger boxes, the next generation will likely be the highest we can go without a change in processor engineering.
Also, to note, no high polygon PS3 game is full 1080p. Even Uncharted is 720p and you can definitely see the polygons in that game even with all the normal mapping and stuff. Next gen should have enough power to at least make the polygons almost unnoticeable which can aid in the immersion quite a bit. Jaggies, polygon edges, and bad framerate makes you feel like you're wrestling with technology and they should all get better next gen (except Wii U).
In the animation trade the term often used as a holy grail was 'polygon per pixel.' This stopped being a goal a long time ago but remains one for real-time interactive game play. If we were still targeting NTSC displays we'd be there but it made more sense to move to higher resolution. The maximized rendering for NTSC would still reveal the limitations of real-time animation and AI. Bumping up the resolution only required more horsepower rather than new techniques nobody has really worked out yet.
A funny thing about the PS3 is that developers are extracting better rendering at higher resolution because they have no choice. The Xbox 360's scaler makes some things pretty effortless, allowing devs to use oddball resolutions internally that provide the best balance of visual quality vs. frame rate. So there are games using a sub-720p resolution and being scaled. But on the PS3 to get scaling done without severe overhead you need to use the resolutions that lend themselves to it. You really need to hit 720p to get easy soft scaling to 1080p.
For similar reasons the new iPad model is exactly double the resolution in each direction. Existing material scales with very little overhead.
If I thought I needed to get out in the sunshine I'd play Boktai.