Whether or not a business suffers reduced patronage doesn't in any way help those whom it discriminates against. The inconvenience and humiliation of being treated differently to other customers is not nearly as insignificant as you imagine.
And contrary to what Benjamin is arguing, there is no intolerance of Christians in this scenario. If a hotel owner (be they Christian or anything else) is obliged to provide a room to an unmarried couple, in no way does it impact on the lifestyle or beliefs of the hotel owner. But if members of minority groups are refused the same services as everyone else, it will have a signifcant impact on them.