I think it has many reasons, some in culture and traditions and some due to practicality.
In our families its sons who bring a wife in our home..yes some places daughters also bring gharjamais, but thats only exceptions..as a rule girls only move to their inlaws. and even in case they are going to live in a separate city, but after marriage they first come home to their inlaws only..so the first step towards change would be.
The boys and girls should arrange their marriage on their own and celebrate it at a neutral place with their own earnings.
After marriage they should shift to their own home..they should arrange for that.
That way neither girls parents need to spend, nor boys parents need to give lot of jwellery and clothes.
Unless the young people decide to be totally financially independent they cant bring a change.
Second thing ..in many families parents spend all their future money on their sons in the hope that once they get settled they will look after them..as is our social structure..But when their DIL doesnt want them they have nowhere to go..After a few years parents will become wise when it becomes a rule, but today they are helpless..so for all the girls who think they cant take the responsibility of inlaws need to state it at the time of choosing the groom.
Till such time that a totally fair system evolves..its the duty of both ..sons and daughters to look after their parents in need..living together is not necessary, they may arrange a separate place for them but helping them with whatever they need financially or physically is their moral responsibility..Its true for both set of parents.