So, my point is very simple:
"Loot rules" are not enforcible and hence they are violated on a regular basis (it will only get worse with F2P).
A loot system that would, for example, generate individual loot for each team member would remove the need for any kind of regulation - but unfortunately, we don't have that in SWTOR.
Hence, I suggest that we only use "need" (and "pass" if you don't want the junk) and let the random generator decide the outcome. While not ideal, it is at least fair.
Personally, I go into a pug assuming that all of the people I group with are considerate and will not
act selfishly. While this doesn't always prove to the be the case, because I treat others this way, I more often than not end up with a group that does, in fact, act cooperatively.
I only ever need on anything that is a direct upgrade to my main class currently in the instance, greed on everything else EXCEPT for gear tokens (Columi/Rakata) that are not for my class -- those I pass on.
I've pugged many many times using the group finder on 9 different alts (4 at level 50). I'd like to think that people who have grouped with me enjoyed the experience and are happy when they see one of my alts pop up again.
On the flip side of this, because gear is so easy to get, I'm never too inconvenienced when someone does act selfishly and needs on something for a companion or alt. It's all a matter of perspective.