That said, I don't think anybody else would've bothered to make retina display available to the general public until Apple forced their hand and made it available themselves...
The technology was coming, it was just a matter of time. Apple are in the unique position of controlling both the hardware and the software, which makes it far easier for them release this in a nice way where the OS and much of the software works well as soon as they made the hardware available.
Sure, it's always coming. Many of us were waiting for someone to make an "iPhone" for a decade. I used to explain to people at work that I shouldn't have to carry a Palm and a phone, for example. How long would we have had to wait if Apple didn't build it? Another 5 years? I'd like everything a half a decade sooner.
Apple gets ripped for not being innovative. What they really do is identify when good technology is ready for mass consumption then ship it. Remember when they went with USB? I was a PC user back then, building my own computers. I waited years before USB became widely adopted on affordable motherboards. Within 12-24 months I'd say Apple's entire product line will be Retina. Hopefully, there'll be enough buzz that it catches on with the Dell's and HP's.
The technology was coming, it was just a matter of time. Apple are in the unique position of controlling both the hardware and the software, which makes it far easier for them release this in a nice way where the OS and much of the software works well as soon as they made the hardware available.