Color is one of those things that's hard to gauge, as everyone's monitor is different, never mind people's eyes, prescriptions, the lighting in the room, etc. A color that's very light on my monitor is plenty dark on Paul's, for example, and some nice but dark colors on mine look black on his. When humans are reading type, black text on a white background is most readable, so unless I am making the text bigger and bold for, say, a birthday greeting, I keep it black.