Well looks like I'm never getting it then Lol and looks like they just lost half their potential clientèle Lol
Nice overuse of lol. And I don't think they didn't lose half of their potential PC fanbase because they only have Windows XP.
But ontopic:
You know, even though it still may be reliable, Windows XP is 9-10 years old now. That's almost as if you're saying "Why the fuck won't Crysis work on mah Windows 2000/98". Seriously, technology changes over time, Frostbite 2 probably uses features that you can't get with Windows XP.
Unless you upgrade, you're going to encounter a lot of problems in PC's modern gaming.