Well, Wii U is deficient in almost every 360 port it runs that I know of. So by your same argument, if it's really 352 GFLOP shouldn't Wii U be "murdering" 360 in straight ports?
If you ran straight 360/PS3 ports on XBO, it would murder them. Instead it's running "next gen" versions, and sometimes struggling, but that's not the same thing.
Beyond that, you're just into diminishing returns to some extent. Nothing on either PS4 or XBO could be argued to "murder" prior gen. Yet, at least.
It doesnt matter what the flops are. Flops are not comparable across architectures, as different architectures have different ways of arriving to the same floating point solutions. Before we could ever hope to make sense of flop performance if we ever DID find a number, wed need to normalize them before we could really get an idea of what we were looking at.
On one architecture, a square root could be a single cycle operation, on another, it could take 15 cycles.
Also, the wii u cpu runs at 1/3rd the clock speed but with a much higher ipc, and is far more efficient (as does ps4/xbone, but they also have 5 more cores). Its very different, and wasted performance, particularly in ports made by understaffed port teams who didnt write the original software are to be expected, even for systems far more powerful than the systems the games are being ported from.
Just look at the disaster that was the silent hill collection HD.
Its true the wii u cpu has no modern simd, and is still stuck with paired singles, whilst the 360 and ps3 still have impressive looking flop numbers. But, the situation is not as dire as many previously believed.
RAD game tools got bink 2 up and running fantastically on the wii u. In fact, it was a surprise to them. THey assumed that since the system had no modern sind, it would be stuck with bink 1, as over 70% of the data executed in a frame is pure simd.
Apparantly, that 750 is the little ppc core that could.
'Added Wii-U support for Bink 2 - play 30 Hz 1080p or 60 Hz 720p video! We didn't think this would be possible - the little non-SIMD CPU that could!'
Its certainly not a powerhouse, but its cpu is not a blackhole of simd performance either.