True enough. Complete SPEC scores for Intel and competing processors would be useful. I wonder if x32 mode solves this problem with SPEC? X32 mode is supposed to give the best of both worlds - all the x64 improvements such as extra registers without the overhead of 64 bit pointers.
I'd have though it would be a good idea to use x32 for most purposes. As to SPEC, that is a good benchmark in some ways, but it really measures what a power user wants to do with a desktop. It is not really a mobile benchmark where you want things to power up quickly, go fast for a moment, and then go to low power again and do some things more efficiently at low power. Getting a good mobile benchmark is a difficult ask which is why I like a review that does a number of tests on mobiles and talks about them.