For us as customers, continuing on with the games being multiplatform as they are now is obviously the better choice.
For them as a business, they gain nothing from keeping these releases off Playstation and Nintendo systems.
Xbox is never going to be a serious competitor for the other two, and PC players have zero reason to switch to Xbox.
All exclusivity will do is take away a half dozen games per generation from 2 far more popular platforms, resulting in a far lower return on investment for games than would have been brought in previously, so the next games the studios make will either have drastically reduced budgets and ambitions, or result in studio closures when they inevitably continue to 'underperform'.
Taking hugely successful multiplatform franchises and hobbling them by tying them to just one of it's main platforms in PC, and the 'also ran' of the console market, makes no sense financially for MS, and puts out about 200m console players who still won't buy an Xbox.
But hey, it's all worth it if those few dozen million xbox owners get to blow raspberries at the majority, while they objectively actually gained nothing, I guess.