Microsofts tools obviously needs to work well on mobile, and I can understand not wanting to maintain multiple code bases, but I think their hurting their users by not doing it.

I know at least one CEO who will absolutely explode if they fuck up his Outlook. He probably have 20 years of business correspondences in there. Is that a good idea? Probably not, but he does. If Microsoft mess up Outlook, then there's very little reason for his company to not look at Google and Gmail, and he probably will just because he'll feel like Microsoft screwed him over.