I think you're severely downplaying the PS4 hardware and talking up the Wii U hardware just a bit there. The first PS4 demos are already showing a noticeable increase in polygon counts, effects as well as much more subtle lighting and shadowing...and the games that are about to be shown at E3 are also looking mighty impressive.
The increase in fidelity will likely be very apparent from the get go this generation because I think that a lot of UE4 PC development is going to scale nicely down to PS4/720 games while the Wii U will be getting UE3 games that look like prettier versions of current generation games.
I'll agree that the Wii U might not get a fair showing for a long time as it's looking like no third party is going to really push the hardware anytime soon, but that's no reason to not give the PS4 credit for being an impressive piece of kit.
Really? A noticeable increase in polygon counts? Right there I can tell that you are either being completely disingenuous on purpose (lying to make a point) or you really have no idea what you're looking at. There was no noticeable increase in poly count in anything that was live rendered at the reveal, and "more subtle lighting and shadowing" or SSAO, can also be done on the Wii U.
I'm afraid any supposed increase in fidelity won't show through as well as you think it will. The PS4 can't handle the main draw of UE4 anyway, and the only reason it won't be created for Wii U isn't for lack of power, they don't want to make an engine for the only Power ISA based console, that is all. They'll eventually bring it to Wii U, just not up front.
The PS4 is an impressive piece of kit, and it will do great things, but there are too many people overhyping and overstating it's capability rather than being realistic about what it will do, which is marginally better than the other consoles this generation. That's it, it will not be some mind blowing difference in fidelity between the Wii U and PS4, and all of the advanced rendering techniques are present on both. Sure the PS4 has a nice GPU, but what it will amount to in game over and above what Wii U or the 720 (also supposedly has a "weak" GPU) is very little to none.