I do carry on only for a few reasons, getting in and out of the airport quickly, I tend to do some train travel and so a smaller bag means I can carry it on and off, and store it above my head. I often get laundry done whilst I travel, it is cheap and easy in most cities. For a long trip I will buy a few toiletries, but for trips under two weeks I can easily manage with small containers. Dragging big suitcases around is simply a drag.