This one is easy - the Run Flat Tires. They are junk. They give a harsh ride, and offer me absolutely no peace of mind if I do get a puncture.
If I'm 300km from a city, and I get a puncture, I can't drive that far on a RFT.
Plus they cost more.
So now I have to drive around with a tire plug kit and a 12V air compressor just to get around the limitation of these crappy tires.
They can give any excuse they want as to why they went to RFTs but they are all lame. It's simple cost cutting for BMW - 4 RFTs is cheaper than the extra rim and tire of a spare.