The white background in the default chatzilla motif is, well, kinda glaring... It was enough to scare me away from it. (I thought something was wrong with it and continued to use an old chatzilla.jar file). Later on I found out that the appearance can be changed. From the casual user's point of view, I think that perhaps the "dark motif" should be the default one? If somebody wants a white background for some reason they can change it.
I second that, dark is so much nicer, putting my vote in for it as well.
Some folks are just as scared of (the) dark. The opinions seem to be very polarized. "Default" is the default because it uses your browser settings, which is also why it is called "default." I'm tempted to WONTFIX this, comments?
i say wontfix, although i am slightly tempted to ask for light as the default motif. light looks so much better with modern. dark looks bad, though it might go better with sky pilot.