You raise a number of points, some of which I think are valid, and some of which I think are problematic. I'll try to respond where I can.
I don't understand why more people don't accept [that certain fields are more attractive to different genders]. Why is thinking that their is a fundamental difference between the sexes and that they are better suited for different hobbies/challenges/activities so wrong?"
As I said in a previous post, I think the problem is artificial barriers to entry in a field/hobby/whatever. If someone wants to participate in activity/field/hobby/etc outside of their normal gender roles, I think they should be allowed to without getting shit for stepping outside of societal expectations. As a female gamer, my problem isn't as much with a lack of female game designers (although I'll talk about that in a minute) as much as the fact that men often scoff at me for attempting to participate in this 'male' realm. I don't need you (hypotehtical male, not you, np2392) to explain console difference or the history of Diablo when I've been playing video games longer than you've been alive. That's what pisses me off, not that I might be in a situation where, out of 15 gamers, only one or two others are women. I'd love to see more female gamers, because I do think many of the barriers are artificial and not actually having to do with gendered differences, but I don't pretend a 50/50 split is realistic or even desirable.
You are seeing this with video games recently and the complaints that the video game industry is sexist, there aren't enough women in the industry, games are not made equally for men and women, etc. Why is it not okay to just accept that video games are a hobby that have a special appeal for males?
This is where you being to lose me. I think, in this context, "sexist" has come to mean two things: The gender split isn't exactly 50/50 (what I just discussed) and larger false and unnecessary institutional and societal differences in the treatment of men and women. Take Mass Effect. I played through it as femShep and was able to have a lesbian relationship. I played through as femShep and was able to have a straight relationship. I played through as male Sheppard and was able to have a straight relationship. I played through as male Sheppard and was not able to have a gay relationship. That's more homophobia than sexism, but is an example of what I mean: an artificial difference in how characters are presented.
Lets use armor in fantasy games as another example. I have no problem with scantily glad women if the men are also dressed in silly and objectifying costumes. But if the least-revealing outfit selection for a male character includes a full suit of armor and the least-revealing outfit selection for a female character is a corset, that's a problem. That's where I'd say the video game industry is sexist.