Anybody who actually believes they chose xbox one over anything else because of 'the cloud' and to retain the IP are, well stupid.
As breedinbull says, it's money. Microsoft chose to fund the game and thats why it is exclusive. Money..Money....MONEY!
If they wanted to retain the IP and keep their indie status, they could've done what almost every other indie dev has done and self fund/self publish or find funding elsewhere, but microsoft paid, the end.
Edit: Moderated - Starcraft