I find coloring dialogue/thoughts, especially since I'm mostly an "advanced" roleplayer with humongous post size 99% of the time, a trouble I don't like to go through. I'd still do it if everyone else in the RP is doing that for consistency sake overall; otherwise I'm more than happy not to bother wasting my time coloring dem lines.

Besides, with good paragraphing and sentence structuring, coloring lines is just unnecessary; sometimes it actually makes reading the posts more difficult and distracting.