There might be something else going on. When Bayer introduced "asperine" they couldn't know that it would became so popular. Some other companies made the medicine and called it the same way. Outcome they see each other in court. But the outcome for Bayer was something they had not expected. They lost there rights on the brand name "asperine" because everyone did know what it was and used it. In other words it became too popular. In short, their success became their grave in some way. After that, the brand name soon was replaced by other brand names and everyone forgot what "asperine" was. They got better alternatives.
Now, what has this to do with exFat? The problem for Microsoft is the same. It becomes too popular and its the only system found on mobile memory cards, sticks, hard drives, camera' s, mobile devices and so on. And this popularity can become a risk for Microsoft. The problem is that they still can ask money for Windows, just because there is Linux, OS/2, DOS and some others. So, Windows is popular, but there are alternatives. This is not the case with exFat. And this is about the same case as with "asperine". So, before damage will occur, they could give some away. If they don't do that and go on the way they did, then they could end up in court with possible much more loss then only exFat. Remind, Microsoft is nothing about software but all about rights, that's how they build Microsoft.