Pointing out lines on the ground to folks walking through should always be courteous. They don't know that kite string is left on the ground by some of us lazy fliers. Generally, kite events are not like flying on our home field with a handful of our friends. Often, it is too crowded to be safe with a lot of our toys. Choosing shorter lines and the right kite is the best compromise.
Space is limited, and everyone deserves a piece of it.
Flying a good dual liner on 50 ft. lines under a canopy of single liners parked at 100 to 200 feet is real close to bliss. If they are not obstacles, they make the greatest eye candy. If you can't spare this, maybe you should be on your home field. And when all the idealism and altruism are set aside, my motives are simple. I do not want to leave my spot on the field because the wind seems better for my single line Rokkaku.