You can actually see the individual numbers for the CPU tests by downloading the baselines from within PerformanceTest. The breakdown isn't as detailed as you are suggesting above, but it is more detailed that just a single CPUMark figure.
I disagree. Only assembly language programmers are going to really understand MMX, SSEx, etc.. And even with an understanding of what it is you still can't tell what real applications use which technology.but I think you are underestimating a lot of other people here.
If we take your argument to the logical conclusion then we would end up with 1000s of benchmarks. e.g. one for 32bit addition of single precision floats, one for 32bit addition 8 bit integers, one for 32bit addition of a deferenced address holding a single word that is in cache, etc... It really has to be brought up to a higher level.
You might also be interested in this short study on the speed and breakdown of CPU instructions.