There is no solution to this :P
There will never be a permanent solution for it but it sure can be improved. A common sense lootsystem works better then a anarcy one. I suggest you look how other MMOs handle lootdistribution, some has created a very successful system.
Looters will loot and you can cry about it all you want... but here is an advise
Make GUILDs with ppl you know and trust
Do Heroics/ Flashpoints with you GUILD members
You are part of the same GUILD and looking out for each other
It might work for some people but not all players has the luxury to be in one that can create level 10-50 groups 24/7.
You take away the Need/Greed buttons and players will feel like they have no say/chance of wining anything good.. so they would stop playing Flashpoint/Heroics :P that much
You think that a system that will help prevent ninjalooting will make players stop playing? I actually think it will be the opposite, more players would want to run flashpoints when less ninjas are around.
You do it to someone else ... same can happen to you
It happens anyways, I never use the need button on items I canīt use but still meet alot of players that ends up on my ignorelist