If I worked on making the big mac tastier would you call that improving the world? I mean, plenty of people eat them and improving the flavour improves their lives.

Ultimately the specific terminology is unimportant. Do we agree that there's a distinction between digitizing books in a way that's accessible to everyone, and working to improve Google products that exist primarily to increase Google's revenue, and can you see why people would want to contribute to one and not the other?