But reading through the piece the only tangible evidence he provides is more spacing between elements that he is pulling up on 5 year old hardware?
Screen density and pixels have improved dramatically in that time frame, we have larger screens, more resolution, and retina display, it's like switching from Analog to HD. Not every new interface will work equally well on old hardware, but that doesn't mean that the interface has deteriorated.
Making something infinitely backwards compatible will ultimately destroy the user experience, as you can't take advantage of the present and the improvements it offers.
The OS is getting a bit iOS-ified - that I agree with, but it isn't forced upon you to the level Windows does, so it is easily avoided.
I would prefer to have a seen a more detailed breakout of the real degradation in user experience, otherwise it's just a complete opinion piece with no real facts or proof points to offer.