Why should we obey ALL Islam rules , when we see some of them are useless?

Why should we do something only because it's in religious? Suppose rights between men and women. Did anyone decide to be a man or woman himself/herself ? Then why should we separate their rights? Beside this fact that equality of rights are executed in western world without any problem. Also suppose expressions about have dog, eat pig, drink wine and so many other things that are currently usual in western world and NOTHING wrong happen about that. Living in this way and obey only because ISLAM say so is completely opposite the freedom of thinking. It's a Blind Life. Does Islam have any defense for its incompatibility with facts and things that we do opposite its rules but has no harm and mistake in it? If Islam base is on thinking, why should we obey them only because it says so?