I can't answer your question because I do not think that it an be changed,
but agree with your sentiment. I find the new scrollbars harder to use. It
is a fix when there was no problem. For Canonical it is about appearance and
maximising content and minimising chrome. I am using Kubuntu and KDE does
not have them, but some GNOME apps in KDE do have them (like Pan); others do
not. A fix could be to re-install 10.10 or switch to KDE and use KDE
applications only. Or you can wait for 11.10 which is supposed to be more
configurable.