In fact both things have been tried. (JOJO have a semidoublesurface LEI. I also read about a company making a multitube LE for getting the oval shape. This was 2 years ago and I never saw the COM product.
I think (not so dangerous) that kites are slow flying devices so the round LE dont bother so much. As the wind gets stronger the kites gets smaller and the LE too.
In windsurfing, cambered sails are more rigid and have more TOP end. Not nesessary good low end. IN fact, a sail or kite for low end power needs deep profile, good for low end power but draggier ar higher speeds.
What do you have seeing at the windsurfing sail evolution? First, especialization (wave, freestyle, race), in the race aspect of the sport you find very big and superstable sails with huge wind range, the efficient profile makes this sails perform well at high wind and board speeds.
Perhaps kites are going two ways: lower aspect with good low end for the average rider and super rigid high aspect kites to be used at high wind speeds for the kite size. These will be the super hang time competition kites. Today we have both categories in some way. I think the gap will going to be wider, you will have too chose between a "freestyle kite" or a "hangtime kite" (superstable, high AR, Big, EXPENSIVE, light, fragile, not for me kite).