Honestly it's a decent idea, something to throw out there. But keep in mind actually most of our banners come from banner contests etc and are made by users in the community. There are only a few that actually have staff characters in them, lol.
The biggest reason I can see for kinda putting this idea to the side is that it's an awful lot of work to change banners and since the admins (Red, Raz, Delay) are the only ones who can actually change it, we'd be putting a lot of pressure on those who are already busy as it is.
A good idea though and definitely something to keep in mind. I agree we need a bit of a makeover around here.