To quickly cut through the fog: workspaces vs. viewports

[Michael Toomim <toomim cs berkeley edu>]

I recently started reading some of the viewports vs. workspaces posts, 
but the threads are millions of posts long, and I have not been able to 
figure out one of the fundamental conflicts.
Would somebody be able to quickly summarize (or point to a summary of) 
the reason for choosing workspaces over viewports in gnome2?
I understand why Gnome should only support one of the two options, and I 
have read plenty of articles stating their differences.  However, I 
can't figure out why, taking into account their differences, people 
decided that workspaces are better than viewports.  Was this a carefully 
thought-out decision, or an arbitrary choice?  Was it something decided 
on the mailing list a long time ago?
Thanks,

Michael