The NFL has a deal with Bose for coaches to use their headphones during games. The problem is, most players use Beats headphones. The NFL had a problem with this and "under terms of its agreement with the league...Bose received a broad set of rights that entitle it to prevent players (or coaches) from wearing any other manufacturer’s headphones during televised interviews."
To me, the NFL and Bose come off as sore losers who are whining because they couldn't get what they want. Beats are what's popular these days and banning players from wearing them might make them wear them even more.