What's the alternative? Bad-mouthing Microsoft and speaking out about how the episodic nature might mean the game will never have an ending? I don't know how true the OP's assumptions are, but it sure doesn't sound like Microsoft let him make the game he wanted-- maybe half of it, at best.
I'm sure Sony, or even Nintendo, would have been fine with D4 just the way it is. If Kinect was integral to the game (controller support proves otherwise, though it may be his envisioned control method, so it's worth considering) or there was some other proclamation besides these broad generalizations every dev says about their exclusivity partners, I could understand, but I find this whole idea kind of silly.
Well-put. I would be all over D4 if I owned an Xbox One, but that's not a possibility. I made a choice in not buying Microsoft's console, so I have to live with missing out on a few exclusives I would like to play. It's tough sometimes when I see games like Sunset Overdrive, but there's plenty of other things to play on PC, Wii U, PS4, Vita, and 3DS than I could ever possibly manage getting around to, let alone consider buying another platform for. So, I bid these games good luck, and will remember them should they be relieved of their exclusivity.