I think y'all are right in two things but I would like to add that both are double sided arguments.
On one hand MB does not build cars like they did in the past, but then again neither is anyone in automotive industry.
Also while I agree MB is for upper age groups, I will not want to drive a "sporty" BMW if I was higher than 40-50 so it goes both ways. That is, if BMW is still a sporty brand by the time that happens!
Only other thing I'd like to add is that while BMW might be innovative, don't forget who the pioneer and patent holder is...
MB is still highly respectable brand, even if BMW has changed to appeal to a much wider audience now.
And just for arguments sake I would take an AMG over an M any day of the year!!!