They must think this will allow them to sell 20 more Windows licenses a year...

Yeah, people are going to get more Windows licenses, but they won't necessarily be buying them. If that's their aim it may backfire.

Most likely they don't care, they are enforcing the licenses and that's it. There's probably a division in Microsoft that has to do these things and that's what they get paid for.

Maybe they are embarrassed about how shoddy they will look in a direct comparison with standard browsers.