The iPad 2 has a smaller, lower resolution display than the other tablets in those charts. Once you compensate for that it still has an advantage, but barely. It hardly leaves the other tablets "in the dust".
You appear to be claiming that this is a demonstration of how much better Apple's custom ARM chips are, when it's just a better GPU in the core, just like Samsung's Hummingbirds in the Galaxy and Nexus S used the next GPU up compared with the iPhone 4. They're all PowerVRs. It's about as technically impressive as us both buying a laptop from Dell and me buying a laptop with a better GPU than yours.
I suppose you could give Apple 10% credit seeing how they bought that much of the company that makes them (again, after starting to use their products) but then Intel should get even more credit, because they've owned more, for longer.
There's two sides to this argument and you appear to have missed the important half. Anyone can slap a better GPU on and get better framerates. Not just anyone can slap on "the next GPU up" and still beat you in battery life.
Everything I've ever read about Apple's supposed optimizations is that they have to do with power efficiency.
Meh, ARM is a space where a number of companies are already in cutthroat competition and no one is going to walk in and totally change the game.
Apple's MO here is pretty clear:
(1) investigate their options thoroughly,
(2) back the best price/performance,
(3) possibly make some optimizations,
(4) then lock up the supply if possible.
...
And the results actually are pretty impressive, iPad 2 leaves every other tablet in the dust:
http://images.anandtech.com/graphs/graph4605/40363.png
While getting the best battery life in the category:
http://images.anandtech.com/graphs/graph4605/40257.png