Add one more to the pile of posters skeptical of Roguey's thesis here. I remember multiple friends that I had no idea were into gaming coming up to me in the year following Morrowind's release and telling me how awesome it was... and then finding out they had played it on XBox and didn't even really know that computer gaming was a thing (also they all uniformly played straight fighters and found the magic and stealth systems unintelligible). If I had to guess, I would posit that Roguey is suffering from some regional bias, and lived in an area that, for whatever reason, Morrowind flew under the radar while Oblivion's release caught fire. This sort of phenomenon was not all that uncommon in the pre-extremely-online-era, especially in more rural communities; I never played a Wizardy title prior to high-school, despite growing up playing Might and Magic, Bard's Tale, and Dungeon Master.
But overall I really don't think the XBox has any peer when it comes to the effect it had on expanding the gaming population of America (and obviously this was not a positive thing for anyone who enjoyed games prior to its release). There are edge cases like the separate advents of mice and 3D chips, or isolated incidences like Myst and The Sims, but none of them had nearly as long-standing an impact. The XBox really fucked things up for everyone who had been in on the ground floor.