Supposedly quieter (which they are), and truthfully, the vacuum actuators are pretty reliable (I could get flamed for this).
When age takes a toll on the hoses, that's when trouble erupts.
MB has since changed that viewpoint, since my ML has electric ones...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car