Writting an opposite sex character

Writing a character of the opposite sex is quite a challenge, but its one of the most exhilarating parts of writing, and as we can see Jane Austen's never wrote about the internal life of a male.

But why is so complicated to write about the opposite gender? Well easy we're completely different and we rarely get together, lets say, we just have different opinions and racionality, that's why writing a fresh character from an opposite gender is a challenge.

So why do writers try to accomplish this challenge when writing a book? 

It's a way of expressing their ideology about the opposite gender, so that way people can give their opinions about what they think of  genders.