An important thing to keep in mind is that GNOME 2 and earlier were developed first and foremost by programmers, from top to bottom. While there was some input

An important thing to keep in mind is that GNOME 2 and earlier were developed first and foremost by programmers, from top to bottom. While there was some input from self-proclaimed "UI designers" and "usability experts", we generally saw experienced C programmers with a strong UNIX and X11 background calling the shots. That changed with GNOME 3. The involvement of so-called "designers" was much more significant. They've been calling many of the shots. Changes aren't being made for pragmatic reasons, by the very same users who use GNOME to get serious work done. Rather, the changes are made purely for aesthetic or speculative reasons. In many cases, they appear to be direct rip-offs of OS X's approach.