I know (... I think I know) that unnecessary drivers aren't active, but on an upgrade, they also have to be rebuilt, etc. etc.
Only thing when it's handy: when you change your video card / wireless device / ....
(however vesa-modus, DSL-line, etc. can help you at that moment to install the right drivers....)
I hope someone knows (in the 2007 - 2009 version, it was still available....)