Should there Be More Women in IT?

I've recently took part in a series of IT industry events organized in the US. My biggest surprise was to notice women are a minority to all these events. I don't know why exactly, but thinking about it, this is also true at work.

There are quite a few women at AXIGEN, but still, less then men. None in tech support, none in software development. Some work as testers, quite a few in marketing, sales and HR. And I have to wonder, why is that?

Thinking back to IT and computing universities, the numbers are the same. A lot less girls than boys. Is it because the field is not attractive for women? Is it because they don't like to have to prove themselves to the alpha males? Which is it, really?

I know from my own experiences that men in IT sometimes have troubling reactions. Some look down on you, as if you had no idea what you were talking about. Some are actually surprised when you know quite a few of the techie toys they play with. Some look in disbelief when you want to learn something more technical.

Of course, on the other side, there are those taking you as you are, regardless of any differences of any kind.

Which do you think are the reasons for us women to be such a minority in this field? Would more of us make a difference and if yes, in what way?