Have you ever used a 30" display? Maximizing windows does not make a whole lot of sense there, especially considering the difference in window contents on Windows vs Mac (ie. self-contained menubar, etc).
That's where the newer Microsoft Windows method of maximizing into 1/2 the screen works well. I'd prefer if it were customizable to work in thirds, though.
I maintain that people think of multi-windowed UI in terms of windows first. Resizing a window to fit the content makes less sense than resizing the content to fit the window. People also seem to get really upset when UI interaction isn't consistent, and the Mac approach means that it varies wildly between apps.
You can drag a window to a corner to get it to fill a quarter screen. Kind of hard to hit the lower corners (it is not the screen corner but the top of the taskbar).