Now, a minimise button I do use, and my windows neatly get hidden away behind the icon they belong to (it's an option in OS X and I love it). Now, when I move my mouse to a corner of my desktop and activate exposé I get to see all of these windows as thumbnails.
Removing minimise is in my opinion definitely disruptive, sometimes it is nice to clear all the windows off the screen, using different workspaces is not always the right answer.
I assume that the overview they are talking about (and having read the linked email) looks and acts like Exposé does on the Mac, while nice, a lot of full screen applications and it becomes difficult to select the right window because the thumbnails get too small. The suggestion offered in the email looks a lot like what Mac OS X does.
I do hope that when Gnome 3.x is available in your standard Linux distributions that turning the minimise button back on is available.