The 16.66 percent generational increase in maximum clock rates is a much larger jump than we've become accustomed to with Intel's new generations of processors.
Remember when we regularly saw these increases every year? How long did it take the Pentium III to go from 400MHz to 1GHz?
Maybe that's not fair though. CPUs increased their power consumption all willy nilly back in the day. Engineers have to be really careful not throw power consumption out of whack with changes today.