My potted view on adding extra ethical clauses to open source licenses: you should totallytry it out! But (and this is something that the GPL's aikido hides), the point of FLOSS licenses is to bypass the problems that ideas of intellectual property insert into the free flow of digital information. So, you get to add your clauses, but you will also end up with the friction and unintuitive consequences of IP law.

This has, historically, Not Gone Well. But who knows what the future holds?