This is the strangest request ever?
I had the same problem with TES 4: Oblivion when it came out. Others did too apparently. Luckily somebody made a nice 'darkui' mod for it and it was pretty popular. I just think it's dumb to make game menus such a bright color. I still remember those horid modless first days of Oblivion; wander around dark dungeon, open ui, face melt

.
Sadly, I did not get used to the F&S menus after an hour or so. I always found it jarring.
Thank you Voso for the gamma tip. I actually didn't even notice that slider there before you mentioned it. I have no idea how I could have missed it so many times. Setting it lower is similar to lowering brightness however, and is not as desirable or as helpful as I'd wish it were.
Theoditus sums up the situation well. I can't turn down the brightness (or gamma or contrast) low enough to make the menus bearable without making the rest of the game too dark.
Ideally, the menus themselves would simply be a darker color. Until then I'll have to keep on wincing every time I open a menu, click on a town, etc.
I just took a quick look at the game's files and the textures are all right there in the textures folder as a bunch of .dds images. Should actually be pretty easy to mess with them. I think at least I could open them and just darken them up a bit. I'd imagine that as long as the name is the same the game will load them just fine.