It's also easier to implement non-gamma correct blending, but seeing as it looks terrible and uneven, Apple so far has not done that.
More so, most technical people don't even understand that one, so good look getting a non-Jobs type to see the importance.
Non-retina displays are going to stick around for years. Not everyone wants high DPI, I for one much prefer working on a giant non-Retina monitor instead, for more real estate instead of detail. I don't know what they put in the water in the Bay Area, but everyone seems to be moving towards a lowest common denominator approach.
This is a terrible decision, and if they don't fix it, it'll be just another reason to abandon the platform.