I agree that that's why they didn't do a simple XBox 2, but I have never in the past 20 years had the thought that 360 starts with 3, so it's the competitor to the PS3. But even with that reasonable limitation guiding their decision, going from OG to "360", "One", and then "Series" is a pretty huge failing to establish a consistent branding. And "Series" in general doesn't give a natural sounding way to refer to this generation as a whole.