Yes it would make perfect sense but unfortunately it doesn't seem to be the case.
As I say ... See the screenshot overlays in this thread.
Oh, my point is that it would be working correctly with 4:3 getting a taller fov if they had defined 16:9 as the new default.
It's hard to define what's right and wrong fov for each aspect ratio. For instance... people wouldn't be thinking Gears of War had a "wrong" fov if they'd never compared it to 4:3.
And while people got mad over the fov for Bioshock... what if the dev team decides to fix it by giving the 4:3 view a smaller fov? That would make 16:9 have a wider fov than 4:3, but it wouldn't actually change how 16:9 looks.
By the way, this comes from someone who displays things in 4:3 on my computer and 16:9 on my 360. So I don't feel biased. I don't really care how whatever aspect ratio compares to another, as long as I can sit down and think it looks fine on its own terms that's all I need.