If you distil it down to its component parts, sexuality is just an arbitrary grouping imposed by tradition.

We look upon Slavery with disbelief. In two centuries time, our descendants will look upon Sexuality the same way.

Yes, this is naive and overly optimistic. People who tried to get Slavery abolished were treated the same - "Well it's a noble goal, but who could change the attitude of that many people?"

As it has been said so well - sexuality is fluid