Why women cannot be bishops

Susie Leafe - Is organised religion sexist? | 4thought.tv

She's gotten a lot of flak, perhaps because it was too short for her to elaborate on her argument, which I assume is on the lines of the following:

Men are biologically incapable of having a baby, so it is not sexist to say they cannot give birth to them.
It is delusional to imagine that they can give birth to children.
Nonetheless, they play an important role in the care and bringing up of a child.
Men and women play (or can play, at least) different but equal roles.

Similarly, women are spiritually incapable of leading a church (let's take the family leadership part out for now), so it's not sexist to say they cannot be bishops.
Nonetheless, they play an important role in the church, serving it.
Men and women play (or can play, at least) different but equal roles.