To be fair, most people who are complaining about ninjas and losing loot rolls are only thinking of themselves. Since the complaint thread stems from THEM losing a roll on something. The issue isn't fueled by altruism. It's fueled by people thinking of themselves and what they lost a roll on.
I'm not, all but a few runs my least geared companion is better geared than everyone (but me) in the group, so I usually pass on everything that could possibly be useful to anyone in the group or their companions. However, that does not mean I do watch rolls and get upset about ninjas. Now when I get a group in the close to the same gear, I will greed.
I even pass on biometric crystals, have over 100 and our guild has between 300 and 400 in the bank. I needed 3 when I first hit 50 on my first toon, but since then I have only greeded until I started worrying about storage space. Still feel like a idiot paying 100k for the first one to make my rakata stim.
I am living proof that you can get very well geared without ever using need. If you are nice and treat people with respect, they will want to raid with you. So for 6 months I was doing 3 raids a week on one toon, until I started to get burned out and toned it down to a one group and maybe a guild fun/comm run.