for the convenience of rolling my luggage instead of carrying it.
i also wonder if i could replace the plastic wheels on the luggage i already own with gel wheels. if i could do this, it would be a lot cheaper than buying a whole new set.
i think roller luggage is one of the best inventions there has been. i remember dragging my luggage getting into the airport and through the airport. depending on heavy your luggage is, this can be a slow process.
now all of my travel luggage has rollers on it. i even use roller carry on luggage when i get on the plane, as well as my luggage 