360 became big because it was released an entire year before PS3 along with it being a cheaper console, not a Call of Duty map pack deal that didn't start until 2010. Most people only buy one console and It's difficult to wait unless you are a big fan of one brand over another. I knew literally one person who decided to wait and get a PS3, everyone else I know jumped on 360 in 2005, regardless of what console they owned before that. When Sony launched the PS3 a year later, a lot of people had already bought a new console within the last year and Sony didn't help themselves with their pricing.
This time around, Microsoft screwed up big time at E3 by revealing a higher price point than PS4 along with policies that people didn't like including forcing Kinect, always online, used game policy. People were pretty upset about it and even though Microsoft eventually changed their stance on these things, it still rubbed people the wrong way. On the other hand, Sony had a much better showing at E3, other than when they slipped in the fact that playing online would no longer be free, but I think most people didn't hear that bit and found out later. Everyone I know who is getting a next gen console at launch is getting a PS4. A lot of people just get what their friends have, so the early adopters will influence purchases next year and years to come.