I kind of like the fact that the hp output from a 2008 M3 is the same as a 2013 M3 (even some limited editions). I perceive that as a consistent brand. One that would not add 10hp per year or per "edition" only to piss off everyone who bought last year's model.
It makes the 2008 model that much more valuable, and subsequently the 09-13 models as well. I think this helps resale/residual value of the brand as a whole.