Actually... a lightly "customizable" ability would in-fact be possible through the use of a multi-theme; ie, devdb's forums use helios-multi (
http://forums.devdb.org); by clicking the little colored bars at the top, it switches style sheets to allow for different color schemes.
Still, that would likely be a lot of work, though then again, furtopia uses fewer images and more things like html-rendered borders and background color and text color, so making multiple style sheets would not be as big of a problem as there are fewer images to mess with than in an image-heavy style such as helios (helios has to have each of its border images recolored for every single color scheme)
