I don't have a platform of choice.
Regardless, it matters for several reasons, personal and not:
1) I can play in my bedroom instead of the living room, if I so choose to buy it on Xbox instead of PC, Wii U or PS4.
2) Devs I like may profit more, and make better/more games.
3) With a more robust offering, perhaps we can get better Games with Gold.
4) As someone whose livelihood comes from studying and researching competition and vertical contracts, Most Favored Nation clauses are an odious feature of bargaining contracts that has had significant negative impacts in Cable TV, for example, and is frequently under review by the DOJ and researchers regarding its negative impact on competition:
http://www.justice.gov/atr/public/division-update/2013/workshops.html