Its actually a way of reducing spoke dishing. Spoke length can be closer to equal on drive and non-drive side, and therefore spoke tension can be closer to equal all around (particularly, higher than normal on the nds). That is the major problem in rear wheel building. The spoke dishing prevents the nds spoke tension from being brought up to a healthy level.

Off-center rims are another way of building dish into the componentry (rims and hubs), instead of achieving it using only the spokes. This is a wonderful idea, and I think all rear multi-speed wheels should use off-set spoke bed rims. It makes the wheel much stronger because spoke tension on the nds can actually be made adequate. One of those great engineering ideas that just hasn't caught on. I think its typically easier to build the dish into the rim than the hub, but these are certainly not a bad idea. What baffles me is the large flange on drive side. Not sure I get that one yet.