It is a legally binding ceremony so presumably you don't want that to be performed by just anybody. The idea that it's performed by someone who is licensed with

It is a legally binding ceremony so presumably you don't want that to be performed by just anybody. The idea that it's performed by someone who is licensed with the state and therefore officially accepts obligations that come with the right to marry other people seems reasonable to me. As to unfairness, maybe it would be unfair if it would be a trouble to find an officiant that is not a religious representative. The way I see it is that allowing religious representatives to perform a wedding ceremony as accepting societal reality that many people are religious and are more comfortable when wedding is performed by a religious representative but in no way it constitutes harm to non-religious people.