I agree with your sentiments and most of what you say, though I do think that society has the right to endorse marriage and reward those who take part in it.
But from my own biased point of view, it seems that it is those on the Left who seem hell-bent on making harmony impossible. It seems that conservatives living in liberal areas have for the most part accepted that their views are in the minority, and can live with it. In conservative areas, however, there is always some malcontent who can't tolerate expressions of the majority. That's why, for example, you have Court rulings that bar a prayer over the speakers before a high school football game in Texas.
The problem with "rewarding" marriage is the reward may result in unintended consequences. An incentive to marry may also be an incentive to marry the wrong person just to receive the reward. However, neither the institution of marriage nor the society in general is helped by people marrying the wrong person and making bad marriages to receive the reward. However, if the reward is valuable enough, people may do these things because they need the reward. The result would be bad marriages and the kind of misery that causes people to doubt marriage completely.
The situation is analogous to the origins of welfare. When welfare began, no one ever thought that a small government check to help a few women and children in desperate situations would be an incentive for poor people not to make their marriages and families work. Even now, liberals try to dismiss concerns about the effects of welfare by pointing out that welfare recipients never lived as nice a life as folks in the suburbs. What they forget is that for people in bad circumstances, any kind of incentive can push them into an otherwise foolish decision. Welfare was hardly a "reward" for being a single, unemployed parent, but it had that effect, and the result was a disaster.
As conservatives, we need to avoid the temptation to engage in our own forms of social engineering. A tangible reward for marriage will not strengthen marriage. A good marriage is the ideal, and with few exceptions, married people will be healthier and happier than single people. That health and happiness inherent in marriage is all the reward that is needed. Other attempts to manipulate people into (or out of) marriage will only cause trouble. We can't control everything, and we can't make things just right for everyone. Efforts to push people into a situation "for their own good" are a mistake.
I hate being single, but I'd rather be single than be married to someone who isn't right for me. As an unhappy single, I'm not making anyone else unhappy. If I were in a bad marriage, my wife and I would be adding to each others' misery. As a single, at least I'll always have the option of marrying the right woman if I ever meet her. A policy that tried to manipulate me into marriage wouldn't be doing anyone any good.
Bill