I am so glad to see that you're going to listen and give the players options to make it suit their own vision.
Mad props on understanding that one size does not fit all when it comes to MMO UI's after you listened to the community as a whole.
The problem people are having is the frequency.
It's every single keystroke in combat that causes the inane flashing.
Not to mention most of the AoE flashes aren't as constant and bright and just RIGHT THERE IN YOUR FACE.