I know how to put them back (though I'm not going to bother, I rarely use Ubuntu anyway). I remember I even did some (very basic) tests with themes in gnome and metacity, while I was trying to implement an FS1ish style to my desktop (sorry, deleted most of the material long ago, maybe I still have some svgs of the icons in case you're curious).
I'm just puzzled as to why they took this decision. That's all. There are no hidden intentions in my post.
EDIT: No, I deleted everything. It wasn't much to begin with, just a background with a grid in perspective, similar to the one in the briefings, for the wallpaper, and some icons of folders and other miscellaneous icons with the original FS1 style, the home folder had that little thing inside it that used to be inside the icon of alpha wing in some briefings, and other things like that. I only did some of the graphics and never got to actually implement it.