My rebuttal, if it can be called that, is that the same holds true for FIFA on consoles, yet Madden is still available on consoles. Meaning, even though FIFA is a world wide brand, the Madden NFL brand is popular enough to justify not only selling Madden NFL but also paying for an exclusive license.
To simplify, Madden NFL sells enough to warrant making that year after year and paying for the branding, considering the presumed lower cost of porting a PC version now and already having the branding, PC sales wouldn't have to be astronomical to turn a profit.