The prohibition of homosexuality has been based on religious opinions of a Christian perspective. The same for the prohibition of consciousness altering plants, chemicals, and "drugs." What do they all have in common? They are opinions of certain religious faiths that are being enforced on people that exist outside of the circle. By circle I mean they exist outside the dogma of that belief system but the rules are still enforced upon them.
That is the nature of "law" the law exists to protect the people and the state/country. The law makers decide what is best for the people. The people elect officials that make the best judgement. This was effective when the Americas were first being constructed, but however now we have moved to a global America. Freedom of speech and religion is a 1st amendment right. Applying religious rules on people that exist outside of the system is a flawed system for modern society. That is why the group wave is changing it, slowly, but it's changing. This is a good thing. It is a bad thing for the ego of the collective mind of law makers. But the laws are destined to change. It is like a balloon filing up. It can only hold so much before it pops.
The system is not wrong and neither are the people. It is just out dated. And the only constant guaranteed in life is change. People change, ideas change, and consequently the world changes. From a fundamentalist opinion one would say this is bad. We are all bent for hell, but I challenge you to question that opinion. Liberating people is better than restriction. Restriction maintains a warped opinion of reality. Think on this. It's your opinion that matters to you. My opinion has no weight on your life and well being. Your opinion is all that matters to you.