I agree, but the problem is that I don't necessarily think that Microsoft should be the police agency to enforce IP rights. Just one example of why is take an app that isn't developed by the IP owner, but the developer may have approached the IP owner and worked with them on development, and has permission to use the IP involved. Microsoft isn't a party to that agreement, and really shouldn't be, since they are just the proprietor of the store where the goods are being sold. That puts the burden of enforcing IP rights on the owner of the IP. Yes, that's a daunting task, and I wouldn't want to have to monitor all of the possible outlets where rights can be infringed, but with the help of people like us in the community, those IP owners can be notified of possible violations, and they can choose whether to send a C&D or not.
Just an example using one of my own apps:
I've created an app called PlusPoints. It is a twist on Weight Watchers' PointsPlus program for counting food points. I have been careful not to use their trademarked PointsPlus name, the Weight Watchers name, or their logo. I think I mention that it follows the Weight Watchers PointsPlus guidelines, but I'm not claiming to be them. I use their formula, to the best that I was able to reverse engineer it, and it seems to be accurate with all the testing I've done, but that's ok, too - courts have determined that mathematical formulae cannot be copyrighted or trademarked.
If Microsoft were in the business of enforcing IP rights that they don't own, would they block my app? I don't know, though I suspect it would depend on how new the guy was who was sitting in the chair at the time my app was reviewed.
BTW, I have never received any C&D from WW. The only action they have taken is to block me on Twitter. Oh - and my app has been in the store for almost three years now, and has 4+ star ratings while theirs has 2, and if you search Weight Watchers in the store, my app comes up third, while theirs comes up fourth. :grin: