I would argue that price has been a factor. Keep in mind that the XBOne was $100 more expensive initially. And I would further argue that brand loyalty has kept the margin from being even more lopsided. Also, we only have to look to the last generation to see Sony making some of the same mistakes with the PS3 that MS made with the XBOne. So similar results should have been expected (and I did expect them).
Could be a factor, but launches aligned - altho PS3 sold a bit slower than X360 it sold at a much higher price and alongside the fastest selling console ever.
The only surprise for me has been how well the PS4 has been selling. It looks like there was a lot of pent-up demand for a next-gen console due to last-gen's extended length
The X360 had been out for longer than PS3.