Much of the problem is that Apple IOS is brain-dead when it comes to handling screen dimensions. Only 2X is supported.
That means overkill - since the only possibility is 2048x1536 due to the primitive graphics system.
The definition of "retina" could be met by a display with fewer pixels - say 1536x1152 - which would be cheaper and less demanding on the hardware.
I agree, though I wouldn't go as far as to say it's "primitive"? Nothing at at all (e.g. Android, BB) is primitive.
Resolution independence means forcing vector graphics on developers. Which is not a bad idea, but it's going to take a while to do it and not everyone will be on board. Makers of Opacity and PaintCode would be happy, at any rate.