Same for the wing. It is optimised for one single case. To adapt you have to articulate it, hence the flaps, slots, etc. At the end you may have many more control devices than a conventional sail. Which sounds good in the first moment, but to adjust them, you need also a lot of input information. That's one of the reasons why BMWO has this huge number of sensors on board.
Sometimes simpler is faster. In one interview, the design of Alinghi 5 said, that they decided against a wing, because they lack the time to sort out all the details associated with. And I am pretty sure that's why the BMWO wing is so conventional/simple (some may not agree, but I mean conventinal or simple in a positive sense).

Well, and sometimes predications can be terrible wrong not only for sails...

Cheers,

Klaus