Sorry, I do not mean to sound like a jerk -- I do have a strong love for this game and the idea of a min UI
It is called damage control. Most people will not get an add -on for DPS meters and combat logs thus less jerks. People who really what that info, they can have it also. Compare to the numbers will not have the add-on, they will be less min-maxers thus less jerks. If it is in the default UI, the number of min-maxers will be much higher. I can become a min-maxer too and play by the numbers very easy, but I learn the hard way -- it is more fun not to burn yourself out by reaching to ever higher numbers and worry about that all the time instead of enjoying what the game is.