The theme is actually a very dark blue, but you are correct it is dark. This was actually a popular request, to darken the appearance, from Vista users that use the console at the back of a theater auditorium for example.
Fear not though, there is a light version available too. Press “view > window themes”, press “load factory theme” and select “artusa light”, This uses much lighter blues and grays. This is actually my preferred theme 90% of the time.
You can use this as starting point to create your own theme if you would prefer. Almost everything is theme-able.