We’re all born free and equal under the law. That means that we may associate with anyone who wishes to associate with us, and also to decline to associate. While governments must treat everyone equally, individuals should be able to make their own decisions on whom to do business with and how — on religious grounds or otherwise. Those who disagree with those choices can take their custom elsewhere and encourage others to do the same.
The prototypical scenario that the Indiana law is meant to prevent is the case of that New Mexico wedding photographer who was fined for declining to work a same-sex commitment ceremony. Note however that she lost despite New Mexico’s RFRA, and her stronger argument was based on her First Amendment freedom of expression (which the Supreme Court alas refused to hear).
For that matter, gay photographers shouldn’t be forced to work fundamentalist celebrations, blacks shouldn’t be forced to work KKK rallies, and environmentalists shouldn’t be forced to work job fairs in logging communities. This isn’t the Jim Crow South; there are plenty of wedding vendors who would be willing to do business regardless of sexual orientation, and no state is enforcing segregation laws.