Hopping is a route, not a series of day trips
Island hopping means sleeping on more than one island during a single holiday, moving between them by ferry, boat or short flight. It is distinct from taking day tours out of one base, which is what most people actually do when they say they went island hopping.
Both are valid. Day tours are cheaper and involve no packing. Hopping gives you sunrise and sunset on islands that day-trippers only see between 10am and 3pm, which is when those places are at their worst.