Do you think Apple breaks the traditional product life cycle because they want to create as much hype as possible to compete for attention with Microsoft's Surface tablet?
I'm sure that was a consideration, but I also think they saw an opportunity to upgrade an existing product line whilst introducing a new one, and to take full advantage of the holiday season.
Having different connectors in the iPhone and the iPad was going to cause some people to delay purchasing an iPad 3. Not all, but enought that it would impact sale figures for the year.
So Apple needed to update the connector and while they were at it, they decided they may as well throw an A6 chip in at the same time.