Hey there,
My suggestion would be to make weight and inventory space family wide when you buy it. Another pearl item that should be family wide is the celestial horn.
I can understand that developers need to make money to further improve the game but there are a lot of other items that people buy.
I enjoy spending money in a game when its not needed to spend money.
They could add 'Family-wide' Weights additional to the current ones. Or create a new Journal that gives us, lets say +400 weight Falily wide.