The thing about trademarks is that they can become invalid if the meaning of the term changes over time. Even if App Store only referred to Apple's when they r

The thing about trademarks is that they can become invalid if the meaning of the term changes over time. Even if App Store only referred to Apple's when they registered it, if the term has become generic then Apple can lose their trademark on it. One of the ways to (attempt to) prevent this is to sue the pants off of anyone who tries to use it generically.