I'm with you 100% on this. Never saw the point of these, and I work on VW's for a living.
The point of the hangers, take for example on Audi's, is that on several models the disc portion of the brake floats free from the bearing hub behind it that has the threaded holes into which the wheel bolts go.
What that means is that unless you use a alignment bar or a screwdriver, and are perfect at putting the wheel on the hub without moving the disc you cannot align the disc hole with the hub hole without taking the wheel back off.
YOu have three sets of holes in play. The wheel, the disc (open holes non-threaded) and the beraing hub behind that with the threaded holes.
It truely is a ***** to get things lined up without the hangers. Even in a shop it takes more time than and avg car but if you get a flat tire late at night in the dark there is no way you are gonna be able to align the holes to get teh spare on without the hanger.
On many if not most VW's, Toureg aside, the hanger can be worked around due to the brake/hub design.
On other cars it's a necessary.
As the owner of such a car that needs it, yes, it is necessary.
I can understand that you "don't get the need", but it is indeed there and it is real.
