I even used keybind targeting in arenas - in fact, I did that back in Merciless and Brutal, even getting Gladiator in Brutal. I played meta arenas since they were released.

Maybe that's where the problem is - you don't think that's possible? You can play against me in arena anytime you'd like, and see if my playstyle is inferior to any other healer in this bracket. I don't need to look at a part of the screen to click it. Wat? I'm not looking at my frames when I'm using them for a macro. There is no delay in my performing of one action versus my performance of another, as you have described. Grid Frames allow me to multi-task and effectively perform two tasks at once. You're imagining a style of play that is far different than what it actually is in reality. You don't waste travel time to your frames. I'm gonna give healbot a go to and see how it jives and the benefits of it. I need to play with it and see if I have a reasonable amount of keybind space available. In 3s though, I do use mouseover on raid frames, but I may end up setting specific party healing macros for each teammate. In general I don't want to ever hard target a teammate as that pulls my dps abilities away from an enemy. When not using voice communication this helps a lot. I also have a target focus's target bind which I spam quite often to be sure I am focusing the same target as my partner. In 2s I never have to mouseover heal anything with this setup. If I have more than one healing ability the macros I use have a modifier to simplify things. I also always keep my focus target as a member on my team. I currently do use mouseover healing over raid frames, which is pretty fast and accurate. I will give healbot a try and see if it is something that would help.

People using addons for arena