I'm not saying anyone thinks women should be powerless. I'm saying that women who speak powerfully come off as shrill, smug, arrogant, where men come off as strong.
I think that really depends on who the person (listener) is, as well as who the woman is. These days, it is so much easier for a woman to be in power than in the past, and men are growing more acustomed to it as well. But the woman also has a lot to do with the way people respond to her. Mrs Bush, for example, would be a person most men would feel comfortable with as a leader, (however, I doubt she would do well in politics). Mrs Kerry, on the other hand, would have many people fearing her (which is why she would do better in politics than Mrs Bush). The only female I can think of off hand that is the best of both worlds is Mrs Dole, who easy to work with, yet also has the political savvy to handle the big league.
Hillary would be somewhere between Dole and Kerry just on this basis, so she is already handicapped in people's perception. Throw on her shady history, and obvious political move to the center to make herself more "attractive" to the voting base (rather than sticking up for what she believes in) turns more people off since she comes across as a fake.