It's pretty dismissive (and logically flawed) to assume, first, that you know what happened better than OP, and

Didn't say that, just gave my analysis. Is that unacceptable to have an opinion? I don't think I dismissed him at all either?

second, that this woman couldn't have just been attracted to OP's willingness to be vulnerable. It's kind of shitty to suggest it's some kind of power play or insecurity on her part.

I'm pointing out why she probably even cared if he was able to be emotionally vulnerable at all.

There's nothing wrong with insecurities and power plays from women. All humans seek power, kind of dumb not to(who wants their life to be worse off with less control? No one).

Plenty of women seek this trait in their partners.

Not plenty, all women.

And not because it gives them power or relief that their partner is weaker or something.

Most women biggest fears is being left by their man.

It means he cares about her, not that he's weaker. Yes it gives her power if a man has feelings for her.

Emotional honesty and vulnerability facilitate communication, which is of critical importance to healthy relationships.

Fully agree.

They are also very important abilities for problem solving as a couple and as an individual.

Absolutely so.

A man who is willing to work on this is a man who likely will be a better team player down the road. It's attractive in its own right.

Yup, and being able to better tap into my emotions better has helped me immensely with both men and women.