The whole point of trapezing is to counter-balance the heeling of the boat. It allows you to carry more power (=speed) when sailing in higher winds.

When you are flying a hull, you want to stay out on the trapeze to help balance the boat. Coming in off the wire would make the hull fly even higher (all else being equal, like not letting the sail out).

As a skipper, most of us will power up the boat until the windward hull is "light" - not flying, but definitely thinking about it. You go out on the wire, sheet in to fully power up the boat and support your weight out there and off you go!