Because 2011 15" Mac Book Pros are reaching their planned obsolescence lifetimes and we're finding out that the 15" Retina MBP replacement requires that we have to spend heaps of extra $ to support the I/O reqs and optical disc needs that millions of folks (and our customers) still have. It's known as "backward compatibility"...but maybe that is passé'.
I doubt existing MBP customers would have been ok with no optical disc, no firewire, no ethernet, no way to upgrade to larger HD capacity...if we had been surveyed on the question (i.e. market research). I think the feedback might have caused them to be less presumptuous..
I like the Retina display...and at least the battery on the new model doesn't drain ridiculously fast. But I never heard a huge outcry for lighter, thinner model than the earlier MBP.
Some posts on this topic fault customers like me for not staying up on Apple's changing design philosophy...huh? That's another ridiculous presumption and wrong-way thinking if customer satisfaction is primary.
Many of us are not happy that Apple is putting on a full court press to force us into the cloud and to make sure we cannot play any media that is not purchased from iTunes (especially after the months of movie download problems they've had). Apple is taking capabilities away and making it difficult on loyal customers to remain so.
Also many of us do not support a "throw away" society...we've trashed the planet enough.