Okay, I'll jump in with my $0.02 worth. Orginality with respect to music is not as straightforward a concept as we might think. For one thing, everyone is composing off the same basic scale...at least in Western music. True, it would be virtually impossible to explore all the permutations of that scale, but it is a common thread for all music none-the-less.
I've often joked with folks who tell me they would like to lean to play guitar that if they can learn about 20-25 basic chords, they'll be able to play about 95% of all rock and pop music (though not necessarily Jazz!). For sure they'll be able to play virtually all Praise and Worship music in a Church and Country Western and Folk stuff. And yet for all that commonality, the public loves the music.
I mean look at Country music. How many tunes revolve around the basic I-IV-V progression with the occaisional vi, ii or iii thrown in for kicks? It doesn't matter if the progression is in C-D-E-F-G or A, (Are there any Country songs in B? :)) Yet Country fans LOVE country music? Why? I think by and large its because of the stories told in the music and not necessarily the progression of notes.
I think the same is true for most Rock and Folk music, too. How many great rock tunes worked off the basic I-IV-V? But we love it. (Louie, Louie anyone?).
All of that to say that I think the orginality doesn't lie so much in the exact progression or note sequences, but in the feel and message and, yes, performance. The sameness becomes more apparent when the performance and message and "feel" are boring or don't capture us. I'm convinced you could have two songs using the exact same progression in the exact same key and one would give you the chills and the "WOW" factor big time, and the other the big yawn!
Of course, we still love it when a really talented group or soloist comes along and breaks the mold, i.e. "Bohemian Rhapsody" or the later Beatles, but we also love it when something grabs us even if its using a progression we've heard a gazillion times. Music speaks way more to our emotions than we may sometimes want to admit. I think the truly original artists understand that and compose their music to acheive that response.