Actualy I did report someone for kicking me for pulling aggro "once" in a low lvl area and this while the healer had it easy to keep the party healed (mp never dropped under 95%).
I reported this and got the message that they felt sorry for how I was treated but they could do nothing about it...
Not sure if they realy care so why even use the report button? I think they only care when there are treats involved or heavy insults.