If you remember the development leading up to Ubuntu 10.10, you might remember the outcry over the decision to shift the windows controls buttons from the right to the left. Well, GNOME 3 is going for something more extreme - they have decided to actually remove the maximize and minimize buttons all together.
This decision was announced by Owen Taylor, who wrote to the GNOME-Shell mailing list:
In the end, I think with GNOME 3 we need to emphasize design coherency and slickness - what is different and better, and that actually is more important than being 100% sure we perfectly meet everybody's workflow. Having half-designed minimization is going against the goal of coherency. And doesn't provide testing of alternate workflows. So I'm going to remove the minimize and maximize buttons for GNOME 3.0, and if it doesn't work out, we'll eat crow, design window hiding right, and add it back for 3.2.
According to Taylor, most of the people rarely minimize windows. People minimize windows to keep the desktop tidy, to find other windows, to save a windows for later etc. All these functions can be taken over by workspaces and activities according to Taylor. Another issue with minimization in GNOME 3 is that the concept of minimization is not a part of the design of GNOME Shell. GNOME Shell does not have an icon stack or a dock for windows to minimize to.
This does not, however, mean that GNOME 3 will not support minimization of the windows. They can still be minimized using keyboard shortcuts.
The decision to remove the maximize button was taken because there are more obvious ways to maximize a windows than clicking on a button according to Taylor. GNOME 3 supports snapping of windows according to its position and double clicking on the title bar maximizes the windows. So, the maximize button is considered to not serve any useful purpose anymore in GNOME 3.
These are no doubt big changes that the GNOME developers are considering. Without testing it it is impossible to have an opinion of the changes they are proposing.
So far GNOME has stuck to a UI which is not radically different from that of Windows and Mac. The changes that GNOME Shell is bringing are huge. Now with the removal of the minimize and maximize button, GNOME Shell has deviated radically from the UI in WIndows and Mac. This is not always a bad thing - but it could confuse people migrating from Windows etc. to Linux.
Nevertheless, it is good that GNOME is innovating in the design of user interface. We will only know if these are the right decisions when GNOME 3 is officially released.