Bluecurve is one of the nicest Linux GUI themes I've used; however, it still uses the battleship grey colors of early Mac and Windows versions. Mac OSX and Windows XP have moved to a cleaner looking white + animated colors style that I think Bluecurve would benefit from using. In particular, menus have white backgrounds with drop shadows and widgets have a distinctive color that changes slightly on a mouse hover. Maybe the widget color could be the same as the selected window border color.
I'm reassigning this to our graphical artist who created the theme. He makes the color and theme look choices. (Chances are he'll just close this bug if he disagrees.)
new themes use lighter background. We will continue to reevaluate themes as time goes on