I wonder why Microsoft doesn't release Halo for the PC. I get the console promotion/exclusivity idea well enough, but to me it's just looking like a giant money cow that's bursting with Dollar milk and really, really wants to get milked.
Hell, even I'd grab a Halo for PC just to see what all the fuzz around this franchise is about and chance is I may like it and buy more titles if they brought it out for PC.
They are already making remakes/remastered versions of the titles, so why not go the whole way and port those versions to PC. After all, exclusivity is maintained for as long as the games don't come out on the PS4, correct? PC is more or less a Microsoft exclusive market too after all, so there's nothing to lose and much to gain.
Hell, why Microsoft doesn't go the extra yards and developes an XBox'ish OS you can install on your PC through which you can play XBox games if you plug an XBox controller to your PC is a question I've asked myself for years already. Sales from the OS and the games AND the peripherals. It's a goldmine!