... but because I can read music quickly and play it quickly, I've never developed the discipline of playing with absolute rhythmic accuracy.
Metronome is fine for working out select problem areas. However, IMO it should not be used as a blanket solution for entire pieces of music. Counting helps to develop one's internal pulse, and that really is the goal: to make your internal sense of time reliable and rock solid, so one does not need to fall back on a metronome to keep consistent pace. This goes along with the points made above: how you vocalize your count, and which beats or subdivisons you select for the count.
Counting is ultimately a surrogate and only becomes really powerful when one connects it with actual physical, rhythmic motion. And not just any motion, either. It needs to be continuous, in order for subdivision and "lilt" to be felt, and not only highlight articulation/onset. This is why conducting or even dance is superior to clapping. Another thing that should be noted is that barlines, note-beaming, and the like are NOT your friend when learning how to apply rhythm because they often times distort what actually needs to happen to produce an even and sensitive rhythm.
Thank you all for the helpful replies. I think like most people, when it comes to most skills, I want to do what comes most easily to me and find a million rationalizations for not doing what I need to do (which probably explains my lifetime history of dieting!)