So it's worth noting that I will never root for the Cowboys to lose during the season. That's why I wrote "why cowboys fans SHOULD" rather than "WILL" root for their team to lose. Also it is why I write this before the season begins, when I can look at the team logically and determine how likely it is for the team to win a super bowl with the current roster.
Considering the three best defensive players of 2013 are not going to be playing with the team this year (Sean Lee, Demarcus Ware, and Jason Hatcher) and that the 2013 Cowboys defense was pretty woeful, it is unlikely to expect their defense to be anything but awful in 2014. Yes there are still plenty of weapons on offense, but from a long term perspective I don't want to see the offense play "just well enough" to keep the team in contention.
Here are my top 3 reason why: