My answer is based on my feelings.
When I first saw the ExpII, I even started a thread asking about this model because I have NEVER seen it... I know... dumb...

The first time I saw it, I was like... This is a Rolex? Stealthy... me likey...
GMTII? Just too similar to the legendary Sub in design... something just does not sit right with me, cannot pinpoint exactly...
At 1st, I was ignorant to the fact that GMTII's design is with input from commercial pilots.
I guess the functionality is there... but the design is lazy...
I would have preferred Rolex differentiate the design for the Sub and the GMTII... but since it has been around for so many years, any design changes have to be done gradually right?
Rolex might be going the "Evolution not Revolution" Porche Design mantra...
If you look at the recent Rolex design trends... every model have it's own distinctive design, latest being the 2011 ExpII (love to own it one day minus the premium)
Correct me if I'm wrong... the recently updated sub and gmtII with the thicker lugs to give the case a more "squared" look, both still use the same case right? Wouldn't in be cool if Rolex evolve the sub and gmtII individually to carry different feel?