Macbook Pros especially received mid-cycle spec bumps. Go to Everymac and take a look. This happened all the time. Even the Mini received slight spec bumps a few times.
Apple can't control Intel's processor release schedule. Either they do a minor spec bump (sing Haswell 2) or they don't release a new Air until "winter" (Dec-Feb).
Not to mention that in the computer industry, which is extremely competitive, which Apple, believe it or not is a relatively small player in, updates their products in a much faster more up to date matter.
it is very VERY hard for Apple to justify a one year cycle, that maintains the exact same price throughout the course of the year, when all the other competitions cycles their products more offering previous versions for far reduced prices.
Sure, when Dell and Apple release their Haswell laptop, at roughly the same time, they're roughly the same price.
6 months later, Dell updates their CPU's. Their current "top end" costs the same, but now features that much (or little) more "oomph". That apple, which is now 'old' tech, is still that 'new' price.
this is 2014, not 1996. product updates are far more numerous from the tech companies than once a year. in Some cases, like the Mac Mini, it's almost 2 full years. I believe the current Mini is only available with the Sandy Bridge based CPU's. Since then we've had Ivy Bridge (die shrink) and haswell (new architecture) released from intel, that brought insane amounts of power saving, energy efficiency, and in some cases incredible performance boosts.
yet, the Mac Mini, using 2 generation old CPU is still 599