It's a survival mechanism, nothing more. They need to be fluid for when their very existence depends upon them being able to mate switch. Consider this the next time you notice how few homeless women there are in your city versus men, or how few sugar mamas there are versus sugar daddies.
Being fluid is yet another way to describe their habit of adapting and adjusting when circumstances change, and doing so in the most effective way they can, given their innate abilities.
Village gets overrun with barbarians and can't escape? Well, can't fight 'em, better learn to blow 'em - maybe they won't kill your children if you're useful enough. Women have been doing this one way or another for millennia and they're not about to stop, regardless of current political or religious trends.
Being fluid is yet another way to describe their habit of adapting and adjusting when circumstances change, and doing so in the most effective way they can, given their innate abilities.
Village gets overrun with barbarians and can't escape? Well, can't fight 'em, better learn to blow 'em - maybe they won't kill your children if you're useful enough. Women have been doing this one way or another for millennia and they're not about to stop, regardless of current political or religious trends.