For rumors, you would only be able to relay a rumor that you've heard (they are recorded in your journal, after all), and your responses would be filtered such that you couldn't tell a rumor that is generated in the region you are in. For instance, if there is a rumor that is specific to Ald'rhun, you wouldn't be able to tell anyone in Ald'rhun that rumor, because everyone there would already know it!
I can also imagine how members of your own faction would want to chat with you. Perhaps dialog can be included where they ask you about a recent mission/quest you were on, and you can tell them about it (maybe even impress them?).
Of course, to make all this actually interesting (as opposed to a rehash of them asking (and hearing) the same things you ask and hear), there could be new information...? Maybe you could even start a rumor.
So, yeah, it's just an idea.
Discuss!