I think if you could undergo a perfect and reversible sex change operation as easily as changing your clothes, it would become simply a matter of fashion - but with that kind of technology, changing your sex would be one of the least interesting things you could do, and new controversies would arise: for example, is it ethical to modify your body to look exactly like someone else’s body? And how far can you go with body modification before it stretches credulity to identify as a human, and what does that mean for the concept of human rights?

Personally I think that would fantastic and fun. Who wouldn’t want to see what life is like on the other side?

95 to 99% of the population...

But if there was no real downside in terms of social stigma, and it was totally reversible? You don’t think most people would want to switch just out of curiosity?

Grow a hollow in a vat and insert the brain?

It'd be prohibitively expensive for most, but why not?

It was free in the culture novels. So, the problem is with the fact we can't do it properly yet?

Also, you mentioned environmental factors, is that thinking based on a paper or similar?

Everything was free in the Culture novels; more interestingly, gender swapping was a built-in biological function that one could activate by willpower alone, and hold in a part-way state, even allowing two people to get each other pregnant concurrently.