Maybe there are some people that have more because they are looking for them. I just pick it up when no one want it or if there is no one around.
I usually write "ROOOCK!" and have fun looking everyone running to the rock, ignoring every enemy/mob/ally that might require their attention.
I think that adding the amounts of my 7 chars I will be close to 40.
The leader of my clan had a good idea. To share all the magnanites in the clan and then make some kind of Lottery to decide who is getting the weapons. I really trust my clanmates so I think is a great idea, but I am not sure that I should participate since I do not have enough rocks (and it would not be fair for them if I get the weapons).
PS: I think it is ok the way it is, Magnanites quest is hard because the weapons must be rare and if everyone have them, they are not special. The weapons should not be too good or it would be unfair for those who can not get them. I guess (just a shot in the dark) that in the future, there will be other ways to get Magnanite rocks, maybe through events or special quests.