You have an odd definition of choice and acting on it if you consider suddenly having the strength to rip somebody's spine out with no warning, preparation, or ability to refuse a "choice." Again, people don't get drafted into unions (at worst, they can always walk away). It certainly is an imposition - giving them tools would mean explaining the situation and the world they were born into, including the risks (of being Called or not), and allowing them to opt in, not suddenly springing it on them.
And we know that in at least one case, it drove an already-damaged young woman further into psychosis and caused the deaths of multiple humans (not to mention the near-death of one of the only souled vampires), so it's not like there weren't negative effects.
Those are two different issues: how good/bad it was for the Potentials to become Slayers, and how good/bad it was other people/the world. Dana was no worse off with powers than without them, it's not the powers that screwed her up. Regarding the choice, I think a Slayer can choose not to use the powers if there are a bunch of other girls with the same powers. This is not the case if there is just one - either she has to follow the calling, or if she refuses, there is nobody with Slayer powers until she dies. I wonder what happened to Slayers who refused their calling (there must have been some over so many centuries, even Buffy was thinking of giving up in Prophecy Girl) - did the Council have them murdered?
Now as to the dangers to the other people - I agree with that, it's very risky to give powers when you don't know who you're giving them to. Simone in season 8 is another example. But come to think of it, it was the same with the Slayer calling over the centuries. It's not like anyone makes a decision who the best candidate is through a screening process; it happens automatically. (Faith in season 3 wasn't the best candidate, either.) For all we know, Dana could have been called just as well if Buffy, Faith and all the Potentials had died in the battle with the First. Then the world would've been even more screwed. Someone would have to kill her or have her clinically dead before another girl is called. And most of those girls died young.
On the other hand, having a greater number of Slayers working together could be a good or a bad thing. The latter when, for instance, Simone and several other Slayers from the Italy squad started acting like local overlords and bullying the local population. This is the danger of having a bunch of superpowered people.
I was always ambivalent about the empowerment spell in Chosen. I don't think it was a bad decision like some do - for starters, it was crucial from the pragmatic point of view, to beat the First; and since the Slayers never choose being called, having them all called at the same time rather than having one girl always face all the pressure makes things much better for them.
But I wasn't too taken with it as a story of female empowerment that it was presented as. It does work to a point - in the sense that I can see it symbolically representing the time when, instead of just "one girl in all the world" (she alone in all her sex, like Virgin Mary), there are more women with power; say, going from having just the Queen, to having more women in positions of power and influence in society. But what it's not is any kind of story about equality or empowerment for women in general. It's a few thousand young, athletic women who get superpowers, and meanwhile what good does it do to the other 3+ billion women in the world? Does it make their lives any better? Maybe it would if the Slayers and Buffy's Slayer Army were having some feminist goals, but they fight demons, they don't get mixed up in human politics (if they did, maybe Voll's fear of them would have been more justified). Not that giving all the women in the world superpowers would have been a good solution, or that it would work for equality, since it would create even more of a gender disbalance in physical strength than there is now. Generally, a story about giving some people superpowers doesn't mash well with ideas about equality and human (women's or other's) rights, so it's probably better not to try to judge them in that context. Which I why the inspirational music and montage in Chosen bugged me.
One of the things I'm grateful to season 8 for (besides retconing Buffy/The Immortal
) is that it did, to an extent, deal with the problems and ambiguities of the empowerment spell.
