The reason resolution (amongst other performance metrics) became a big deal is because last gen, PS3 was chided heavily for having "inferior multiplats" so the 360 was the better console because it was "the best place to play multiplatform games". And then, when this gen came around, when those advantages came to PlayStation and left the Xbox, those same people were saying the differences "didn't matter", all of a sudden. So, I'll admit, it was a "how's the taste of your own medicine?" type of deal, when discussing multiplatform games.
But in reality, they really "didn't matter", at the end of the day. The only reason these things became an issue ("resolutiongate" for example) is because of blatant hypocrisy from many in the MS crowd, downplaying the performance differences now, but blasting the PS3 last gen. And even worse, some people must have had short term memory loss, because when it's brought up that MS fans were on Playstation's ass last gen about not being equal to the Xbox versions of games, some said such activities never happened, as a means to further the agenda of "these differences don't matter" (as in, they say PS3 was never shat on, so why do such differences matter this gen?)
TL;DR performance differences being an issue is because of hypocrisy.
