If one leans one body either more or less than the bike, then a lateral loading is being placed upon the wheels. Has anyone looked into how significant this is? Bike wheels are really not designed to take a sideways load, as found by soap box racers having wheels collapse mid corner.
If ones body is in line with the bike then the forces are all directly in line with the bike & therefore act in the direction in which the wheels are strong.

I'd be surprised if having ones body 'off-centre' produced enough lateral loading on the wheels to be a problem, but just curious if anyone has done any maths?