SF is the literature of the theoretically possible, and F is the literature of the impossible.
As for collaboration - I have done a lot, 26 books, and found publishers increasingly resistive to them. It's not that the books are bad; editors won't even read them.
I turned my home state of Florida into the Land of Xanth.
At present I answer about 100 letters a month, and read 300 emails.
Robert Jordan... is a lot of writer
It would be easier to write a novel without reader input, but I feel the fiction is richer for it.