The Haunting Question - WHY ???

My wife and I have this debate quite often and I have no clue why is the system set up this way? I appreciate what Indian traditions and customs bring to the society, as most of the customs have scientific reasoning which we are not aware of. The rediscovery of the same from the modern society just reiterates that the customs are there for a reason and we might not know it or the previous generations have interpreted them in their own way, accommodating to their needs and fancies. I cannot ignore the valid point which my wife puts across during the debate and I cannot logically defend the stance of the society and this question haunts me and most of the husbands in the world (at least in eastern cultures) I guess. The question is ‘Why is that, only girl has to come and live with husband/husband’s family and why NOT the other way round?’