Pokemon is world wide success and features deep turn based combat and is about as related to this game as your MMO. Its GUI is simple accessible and efficient, certainly better designed than your proposed ideal.
Let's discuss the problems
- clearly it's optimized for a 3xxxx by 2xxxx monitor. On a smaller screen those "buttons" on the bottom are essentially 20-30 pixel dots. If you have vision issues, this UI doesn't work for you. People are already complaining about pixel hunts.
- allowing you to create the hundreds of macros that you think everyone should train their muscles for requires complete rework of the key listener modules since the current system doesn't support anything like that. I already had an analogy about the feasibility of implementing a yachts control system on a car. Also I'm guessing you have use of all your faculties, good for you. There are gamers who do have mobility issues, with their hand/arm, and I think they are as deserving of playing this game as anyone else. A heavily keyboard dependent UI would cause issues for them
- ideally yes, we all should be able to tweak the hell out of the UI to meet our own individual requirements, but this game wasn't made with the budget of WoLK. A fluid UI requires you to devote a lot more of your develop cycle resources than a static one. The developers already made their choice.
- if your suggestion isn't practical, then all we are talking about are pipe dreams. Pipe dreams aren't useful when people genuinely want improvements to be made.