I always found it odd that at the end of any given roulette or trip through the duty finder I was only given the option to give a single commendation. Players tend to give them to either the healer or tank partly because of this limit.
What I would suggest would be to allow everyone the chance to commend as many players as they want to, and for a small bonus to be applied as reward based on how many were received. The reason for this would be to recognize the effort of everyone in the party and to encourage civil behavior.