I'd do that only if I were left handed and wear the AW on my right wrist. I think the crown being on the bottom looks funny.
And the fact there is not one advertisement, much less official Apple PR photo of the watch with the crown on the bottom left speaks volumes about Apple's feelings on the design. I'm sure it pains Jony Ive to have to accommodate "leftys" by compromising his design.
Aside from the "contortion" comments, there's another problem with the crown on the bottom, and that's accidentally hitting it when attempting to press the "friends"/"Pay" button. Since most people tend not to use that button much, it's not likely currently a problem, but certainly goes against the grain of the intended design either way.