From the point of view of nomenclature, surnames can't be changed. If you don't use the first name, it means that it is fixed in nomenclature. Therefore, the quality of your name can only be evaluated by the third word. It's really difficult to choose a good name.
If you choose three words, you can't change your surname, but you can choose the first word and the second word of your name, so it's much easier to choose a good name.