There is no solution to this :P
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
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
That green/blue/purple/orange what ever drop... is worth more to someone then you can sell it for as Credits....if it is of no use to you.
Dont understand? .. ok leme try again
You are SAGE ( Willpower ) and the drop is Cunning ( Smuggler ) ... it may be an upgrade to Smuggler guy and if you loot it you can sell it for 200-300 creds... is it worth it ?
After all this is a MMO what comes around goes around :P
You do it to someone else ... same can happen to you