I think the commendation system is fine as it is, if you could give everyone a comm, it wouldn't a nice surprise seeing a comm after a duty, but be expected. You give it to the player which left the most positive impact on your run, whether that is busting out high DPS, tanking lots of mobs, healing through a dicey situation, making them laugh, being helpful, giving them buffs etc.

Yeah, sometimes you wish you could give it to a whole party, but ultimately you have to choose which ONE left the biggest impact. Me personally, explaining fights and being helpful to new players will earn you a comm from me, otherwise I will be keeping an eye on the other players and see which one I think should have one (if anyone at all)

Never expect comms, they are a nice surprise for being a good sport, just play well and have fun.