Homosexuality should be outlawed as it is against the law of God. Western nations used to, until the 1950s and 60s and the age of apostasy set in. It is the metropolitan elites that set the agendas today, not the theocrats of old. The metropolitan elites are all atheists, except perhaps for certain Tea Party folk.
Why?
1. Where do we draw the line between enforcing cast of mind and action? Especially in matters as private as those that occur within the confines of the bedroom.
Why? People should not be convicted concerning who they are but rather what it is they do. Homosexuality is something hard to prove beyond all reasonable doubt. If we start accusing and convicting people on so flimsy a basis, then how much longer will it take before people point the finger at others and falsely accuse them to get them "out of the way."
I could, for example, accuse anyone on this forum of being homosexual in a court of law and potentially ruin their lives based on a flimsy assumption. This is a dangerous legal prospect that was not common in the days when it was outlawed, but has more potential to resurface now.
2. It has been tried before and it has failed to ensure the morality of society generally speaking. At least based on the results. Perhaps there was a mitigating influence back in the day.
That said, I'm not dead set against the idea either. It would have to be one of those general moral laws that is borderline unenforceable.