I am definitely bummed by this. I'm paying the same amount of money for my PS4 edition as the people who are buying the Xbox One edition, so why do I (and every other excluded system player) have to wait longer? I understand EA is trying to make more money by giving Microsoft "timed exclusivity," but they could just as easily lose money by alienating everyone else.
First, DAI is being released on five systems (PS4, PS3, PC, Xbox 360, Xbox One). From the various versions of this story I've read, either Xbox One solely will be getting the content early (thereby alienating 80% of their players) or Xbox One and Xbox 360 both will be getting the content early (thereby alienating 60% of their players).
I'm not saying we neglected souls won't buy the DLC content eventually, but there's a chance we'll wait until it goes on sale or may avoid purchasing it all together. I am such a person. If I hear that a DLC sucks from enough reputable people and even get to play it on another system, I will wait for a price drop. Or I may refuse to buy it at all. My money is too rare and valuable to waste. So, I suppose the delayed content could be good in some respects in that if it sucks on Xbox, I'll know not to waste my money.
However, despite my annoyance, I will not ever consider cancelling my pre-order, which I've had since the first day pre-orders were available. It was a great day. The Game Stop employee and I geeked out for a good 15 minutes. 