I hear you up until this part of your post. Just because the govt gives you a license to do something dosent necessarily mean that govt thinks its good. For example: one needs a permit to shoot and distribute porn. It would be one thing if govt just permitted people to own porn but the govt will actually aquiesce to the creation of porn, does that mean that the gov thinks porn is good, probably not. After all porn intrudes on the sanctity of the conjugal act and their is no love between the two actors who are merely being used for their bodies.
I see your point, however I would maintain that there is something fundamentally different between a business license and a marriage license.
The entire purpose of the business license stuff is to regulate businesses and keep them under control. A specific company seeks a license so that it can legally do something, true, but the license exists to make it difficult to do things - the procedures you must go through to get one are obstacles, and by overcoming them a business owner (theoretically) demonstrates that he is competent to do run the business in accords with public safety issues or whatever other restrictions the law requires.
A marriage license is a whole nother thing. Whereas you seek a business license in order to do things, aside from governmental regulation, whic you would be able to do anyway (sell food or whatever), you seek a marriage license so that the government recognizes that you are in a special state that merits benefits specific to that state.
For example, why should a married couple get tax breaks? Not just because it would be helpful to them - it would be helpful to give an alcoholic tax breaks because he spent lots of money on beer. But not having money because you bought too much beer is not recognized as a good reason to gain special tax privileges, whereas raising a family is.
Why is this? It is because the standard model of the family is considered to be a good and worthy enterprise, and so should be helped, while alcoholism is not.
That is, a marriage license bestows privileges that in the absence of a marriage have no reason to exist, while a business licenses just recognizes that a company is competent to do whatever they are doing and allows them to get on with it (and incidentally, makes it easier for the government to collect taxes). The government does not try to judge and regulate the competency of people to marry.
The nature of the marriage license says that a marriage is a good and worthy enterprise because of what it does and why it is requested. You tell the state that you are married, and they fill out some forms and say “great! you are now entitled to x,y,z because you are now married.” There is no reason to do this for homosexual relationships. That the people involved really want to is not enough.
As an aside, I would hazard that governmental recognition of immoral businesses - even taken as a grudging acceptance of the fact that the government should not stop a specific action - has in some sense given the impression to some people that the things are ok. That is, dirty magazines may be seen as less despicable now than in the past partially because they are visibly tolerated by the government. What we are surrounded by begins to seem normal, and it is hard to argue that such a normal seeming thing is terrible. But that’s another issue, if a tangentially related one.
