I define a clicker as someone who routinely and consistently activates regularly used abilities (as part of a rotation), for most, if not all, of their non-cooldowns.
I define a keybinder as someone who has bound every ability in their rotation (or the entire gamut of healing and tanking abilities), but may still click on things such as 1+ minute cooldowns (trinkets, the standard 2-3m DPS CDs, etc.) For things such as Bloodlust, Time Warp, etc., those abilities are ideal for being non-bound to prevent accidental discharge or premature elustulation (we've all experienced it at some point... you're just standing there, listening to your raid leader talk, buffing up, and all of a sudden... RAWRAWRAWRAWRAWRAWR!). Those things should go somewhere else, in an easily accessible but unbound place (or bind them, but place them nowhere near your regular bindings - the numpad is a good place for those).
I raided Top-100 US for a time in TBC as a clicker. So it is possible to succeed with this mindset, but things weren't as varied as they are now. I was a destruction warlock who scrollcasted. Me clicking was putting dots and curses up, then spamming my mousewheel for shadowbolt spam. Anything other than shadowbolt was moved to, and clicked on.
Now I'm a keybinder (the button gaming mice introduced since WoW's inception have been a miracle for me, as I couldn't quite grasp binding on my keyboard). I have, through practice, been able to bind 1 through 12 with both shift and, depending on ability, control modifiers. As such, as I have three full rows of action bars I'm able to activate without needing to look down at my bars aside from noticing time remaining, and can keep my eyes on the action.
Before: Staring at buttons/bars the majority of the time, and glancing up at the action.
Now: Staring at the action the majority of the time, and glancing at my bars.
I'd like to get to the point where I can hide the bars I've bound, but I like the visual reinforcement they provide in case I have a brain fart and forget, for whatever reason, my binding for a particular ability.
Now, to make this even more interesting - does anyone find any validity in the following statement?
Former clickers make for better healers since they're used to looking at (action bars/health bars) and glancing at mechanics in an encounter.