We should not miss a single simple point: we pay for Microsoft Word and write stories, reports, etc... Then we put our stories on sale. This is the true nature of relationship in these middleware things.
What Unity does today is not accepting this nature and trying to cheat on this. And they do this very obviously, the words and language they use clearly say this ("we don't want revenue based, we want this..."). It is so clear, it is so there. This attitude suits mafia, not a legal business.
So, we all should have an ethical stance against this. That simple! It is not even about money or all of those other technical issues.