Nice thread, OP.
The "ALL" function for the air con. I usually drive alone (M3 drivers have no friends, etc.) so it's completely useless to me, unless I want my briefcase to be sitting in a different climate.
And while I'm on the topic, why is there a hot/cold dial above the AC vents, when I can adjust the temperature?? That is a layer of redundancy that is simply inexplicable.