Don't forget that as far as BMW is concerned, they aren't terribly interested in the customers that keep their vehicles for 100,000 - 200,000 miles... they want the lease business and those who trade in for a new BMW every 2-4 years, e.g., your idea of how long a car should last and BMW's are not necessarily the same, and your goal and BMW's goal may also differ.

By going to lower service requirements, it makes ownership easier, more pleasant, and less expensive (outside the US) for their target market... no need for service, and the associated hassle and cost to bring it into the dealer, until 15,000 miles is a selling point to many buyers. If the negative effects are not going to be seen until 100K, well, I suspect Marketing would push for making their "frequent trader" customers happier.