I've got factory alloys, supposedly coated. Seems everytime I wash my baby I notice more pitting on the wheels

Either the coating ain't that great or the brake pads are made with acid!!!!! This is the first time I've had this happen and I've had many sets of wheels on different cars, both painted and coated alloy

Never had a problem.
There was a thread on this site about this very problem along with some fixes but can't remember which forum it was in. I think someone suggested using a Scotch Brite pad to remove the pits but I don't know which is worse, pitted alloys or scratched ones!!!
The common answer from BMW seems to be that, as you say, the wheels get hot causing the components in the brake dust to eat into the alloys

I ain't buyin' it!!!