With disc brakes and the newer axles, its a little more of a pain to get the.front wheel off. You cant just flip a qr like the good old days. With any new axle thats 15mm or 20mm, you have to unthread the axle, pull it out, remove the wheel, then thread the axle back in to the fork to attach the bike to the rack. Plus some bikes have regular qrs, some have 15mm axles, and some have 20mm axles. Id rather just design it to clamp the tire instead of having to remove it.
Doss, i do share your concern about tweaking the wheels.
My wheels see more side stress each ride than they will evrr see on the rack.