a) it can fit many more default programs/shortcuts
I can actually fit more of them shortcuts on the desktop itself, the start menu adds to organizing other programs that you don't want showing as a "desktop shortcut".
b) it can display more search results
Most of the time I only need to type in a few letters and the program I want is there, I don't think more search results is a benefit really... at the same time the whole screen hasn't been covered up.
c) it will allow you to allot desktop space to "start menu" space by simply defining where your shortcuts lie
I don't understand why its so good to get off desktop shortcut icons.
When I want something I just type it instead of seraching the start button tree. I find it more convient
You can actually do this with windows 7, i do it all the time, also in the exact same way. Press the win key and start typing :P