A graphics benchmark is supposed to be a definitive indicator of graphics card performance. Optimising for a graphics benchmark does not 'enhance the user experience' in any way, it is only cheating users, that is the whole intention of the exercise. It is a cheat. Optimising for games is different as that IS 'enhancing the user experience', because they want decent games performance. How many people do you know who would love a graphics card that only performed well in benchmark tests?
Furthermore, ATI and NVIDIA are the two biggest graphics card companies. Once the benchmark designer people cave in and allow them to 'optimise' for their software, they're shutting out the smaller/new competitors whose time is more critical.
It's like a teacher saying to a parent "your son is great at maths! Sometimes he has a few problems remembering the answers we give him to the exam questions, but after some prompting, he got 100% correct! Isn't that great?".
