Certainly with all the imagined legal expertise on HN, someone will answer. I have no expertise, but here's a shot at least from a moral point of view and based on some limited legal and political principles:
1) It can't wait because people are suffering now, today. Read Martin Luther King's 'Letter from a Birmingham Jail', where he points out that people who are not suffering always helpfully advise the oppressed to wait until later, 'until a more convenient time'. After I read that, I began to notice that pattern often.
2) We're not a democracy; we are, and this is essential, a constitutional democracy. Democracy is mob rule, or as someone said (Isaac Asimov?), 'democracy must be more than two wolves and a sheep voting on what's for dinner'. The Contitution, the Bill of Rights in particular, protects minority rights. It's not up to legislatures or the majority to grant or take away those rights. Civil rights are purposely excluded from the democratic process.
3) It's disingenuous to describe an issue of civil rights and the long-time oppression of millions as a dispute over licensing. Was segregation about hotel accommodations? Slavery and women's rights about employment disputes?