Re: Microsoft simply cannot afford this to happen
Please imagine this on a smaller scale for a moment: you give out a pre-release version of an accounting software you wrote for a client to get some test data in more real-life scenarios. On the next meeting you casually mention to them that their login problems are probably related to the fact that they tend to press TAB too many times and thus jump over the "Login" button to the "Cancel" button. "How do you know that?" they ask. "Well, this test version logs all key presses," you reply, "We mentioned it in the release notes, too. You know, in section 53."
Will your client appreciate your (totally valid and useful) testing feature? Illogical or not, most won't. It goes over a certain line. If you want real-life test data, then you are expecting your users to do the same things with your software that they do in production environments, at least to an extent. That does not mesh well with key loggers of any kind, because at the very least it creeps people out. And that's not good for the image of your company or your software, as simple as that.