Judy,
I like your idea for a couple of reasons;
1. As a big Polynesian fan, I never liked having the wedding pavilion ruining the view. I don't like the Grand Floridian being there either, but that is not going anywhere.
2. If they moved the Luau to where the wedding pavilion currently resides, that would make room for the Villas at Disney's Polynesian Resort! (Yes, I am a Vacation Club member)
Of course, none of this will ever happen for a couple of reasons;
1. It would cost $$$ that Disney seems very unwilling to spend. It is also $$$ that they will not see a great return on.
2. The logistics of getting wedding parties out to an island by boat would be difficult and time consuming.
But, hey, we can dream, can't we?!
Mike