Sony also had the only sub $1000 blu-ray player, which is (while slow and loud) still a decent blu-ray player today. At $250, you get a game system and a blu-ray player. That also helped sell the PS2 years prior. It was a decent DVD player when DVD players were expensive enough, the combo gaming system / player was a factor. 
That has had an impact on sales. Exactly how many sales that helped Sony catch up? Who knows, but you can't discredit that effect. This time, MS is trying to get the jump, so to speak, on Sony but having HDMI passthrough and available (if the companies allow it) cable integration. They are banking that will be the next home entertainment frontier, since blu-ray is probably the last disc based media format we see. 
I still think it is far more likely with yield issues, MS will just buy more fab time and lose more money up front (because they can afford it) than cripple their system in a few years. But, MS has made mistakes before (Windows ME for example).