See, this is the closeminded perspective I am talking about.
We're not talking about number crunching. We're not talking about min-max. It's a matter of three things:
1. Establishing you've actually done damage.
In PVP, as the OP has stated again and again, it's impossible to tell what damage you have done to a target and what damage other people have done to that same target. It's impossible to tell if it's your ranged attack doing damage or another factor.
2. Ensuring skills are working as intended.
Without seeing the numbers in a combat log, we have absolutely no way of knowing if skills are actually operating the way they should. I've seen it happen a hundred times in other MMO's- bugs happen, and the only way to be sure is to see the combat log and compare it to the tool tip for the skill. Devs don't have the time to track this stuff on their own- they need our input because there are literally hundreds of skill combinations and there's no way to test them all.
3. Creating the best build for you
Lots of people are not really good at picking skills. What works for my playstyle the best? Well, I can guess based on the tooltip, or I can get some skills, go out and kill some stuff, and compare the damage I'm doing with (x) combo of skills vs. (y) combo of skills. Now I know for sure which ones do what I want them to do without guesswork.
It's really simple. And I'll reiterate, with the game set up the way it is, what you're scared of happening is very, very improbable. With every class being influenced by their racial skills, the weapon they use, the armor they wear, and all the different guild skills and pvp skills available, there will not be a cookie cutter build. There are hundreds of combinations.
People will still try to make cookie cutter builds. There will still be downloadable UI that will give them the numbers. Adding an option in the game will not stop people from trying to do it. All that does is make it less frustrating for those of us who choose to use it from having to re-download the UI every time there's a patch.