OK, you might not have a clue what I'm on about here but bear with me. The Hofmeister Kink is a small design feature that's appeared on every production BMW since 1961.
Look, here it is. In the circle, a small, forward angled cut-out at the base of the C-pillar.
So why has it been dropped? Because BMW are bringing out a front wheel drive car - the i3 - which, as well as having no Hofmeister Kink, sports a floating roof. Basically they've avoided the subject of not having to put the Hofmeister Kink in by having no C-pillar at all.
Here's the i3, as captured by www.germancarforum.com
www.newmediacampaigns.com put together this handy image which shows the Hofmeister Kink in action on all BMW compact executive cars since the 1500.