Gnome's (and OSX's) spacial mode was rubbish. The whole philosophy of MacOS's Finder ("spacial mode") is to hide applications from the user, and make the whole user experience document-centric. The user opens documents and manipulates them without having to worry about what program they are using to do it.

Wonderful though Linux is, it's applications are not consistent or mature enough to support a totally document-centric UI. Microsoft could achieve that with Office, but they would probably be accused of over-integration, and hit with the anti-trust stick.