I was playing CNJ last night and on several occasions I wouldn't get any, so I can say firsthand that it doesn't go to the healer by default.

I hadn't really played CNJ much until last night and I did notice that as adjusted my macros and ended up being able to do more that I was getting commendations a bit more regularly. It does seem a fair number of people are giving commendations based on how well they play.

In the few parties that were talkative, I tended to get at least one commendation. I'd guess being friendly in chat's an obvious way to get remembered for a commendation.

Who did I give commendations to? About half the time the tank, if they were decent or friendly in chat (so many silent DPS out there). Other times if the tank was acting like a DPS or was always rushing ahead of the team too much I'd give it to the DPS that kept it together more than anyone.

Granted, I was working on leveling CNJ (now 20), so this is purely my observations from very low level stuff. Take from it what you will.