The problem is not only the Asmodians, but also that there aren't enough chests for everyone apparently. Yesterday I spent nearly 1 hour together with a group to kill the Red Nosed Granker King, then half an hour later some other Elyos came and helped, and at the end I didn't get any chest because I was half a second too slow to begin looting a chest.
I think this system of spawning boxes is not fair at all as anyone who happens to be there at the time of the Red Nosed Granker King's death can loot them, no matter if they helped with killing the boss or not. I was lucky that my group shared the income they made with a Tempering Solution one of them got, but I think that's an exception that someone is that nice.
No matter how you put it, spawning boxes is unfair as it invites people (of both factions) to steal / leech, and many people are doing exactly that.