a quote by Alan Kay “simple things should be easy and complex things should be possible” and it is considered one of the biggest API design principles but actually it doesn’t just apply to apis. You will notice it applies to every well-designed product. Take Google Calendar: you can click to add an event you can drag to make the event shorter or longer you can drag and drop to move  it to another time slot or or you can click more options and do whatever like have it repeat every third Sunday on a full moon