That's a great point. I was talking with Doug Schepers and when I noted the resurgence of SVG that's what he said... "oh, I think the Retina screens brought it back" - it is true, SVG is beautiful on Retina screens, there are SVG Test Suite examples where the raster "it's supposed to look like this" image looks very bad next to the SVG side on a retina display. But I think the ubiquity of SVG in browsers was clearly happening before retina screens were widespread. No doubt it is a factor in adoption.