Tesla & Elon Musk have always been about doing things BETTER THAN old ICE cars. Elon has openly said he sought to make the Model S most compelling car in the world -- and he has, as is widely recognized.
But on the Model X, the Falcon wing doors, while definitely an improvement over old style doors in egress / entry for the back seats, do create greater interior exposure to the elements simply because they create a much larger opening than old style doors. In response to a question on this issue, Elon himself said something to the effect of well, even with other door styles you do get rain etc into the vehicle, but the Falcon Wing door does cover the opening.
Yes, the Falcon Wing door does protect from directly vertical rainfall. But rainfall is almost always is slanted. So let's make the Model X BETTER than other cars: prevent rain from getting in. Think "Patio Shade."
As the door opens, if it's raining or if there's snow on the car, an umbrella-style or accordion-style or even simply hard plastic extra ~18" of 'patio shade' extends out from the door on both sides; it retracts as the door closes. Make it with a fail-safe collapse-back function (eg spring loaded or electromagnetically driven to close -- it 'wants' to close.
Then with the door open, you can stand there comfortably even in fairly heavy rain, with absolutely no ingress of rain.
I'll probably aftermarket develop this if you don't OEM it, Elon. :)