Would "I want to make the world a better place" work?
No if I was the interviewer. First of all - we all f*ck the world and I definitely don't trust people who don't f*ck the world. Environmentalists, right or left activists, vegans, animal or minority right defenders, religious or antireligious maniacs, I keep them away. Being loyal to the employer is enough.
Secondly - people are conventional, they repeat what they saw on tv. I'd like to hear a frank answer. Being frank is very important while working with a team.