

Sometimes it does take a little while for them to trigger the dialogues, but you probably should have heard some of them by now. I got less of the ones with them talking to NPCs like shopkeepers on my second playthrough than I did on my first, so there might be a random element to it as well. I had MacCready talking to everyone on my first run. Try taking him the Dugout Inn, the one with him talking to the guy who gives you the Confidence Man quest seems fairly reliable for working. Just stand around near the counter a while and see if anything happens.
For Deacon, have you tried killing an NPC to see if it'll trigger him to go hostile? It usually brings up the menu to dismiss him somewhere. (Just keep a save before you do it, but it's worth seeing if that will cause him to go back where you tell him or not.)
Thanks for the advice. However, I have waited around for some dialogue to trigger and it simply has not. I actually did have Mac with me a few days ago and went to that same inn; no dialogue even after five or so minutes. I know for certain that my companions did comment during my conversations with other people, but never exchanged any words with anyone else or went through a scripted reaction to a unique location...well, besides during Boston After Dark where Deacon talks to H2 and that runner dude.
That being said, I've accepted that the dialogue triggers are thoroughly f'ed up. I wouldn't be surprised if the dialogue did trigger but for whatever reason didn't play out on screen. I've heard about some other having the same problems too. It's just a shame, if only because it's an obscure problem that probably will never get a real fix.
...About Deacon. Once I actually attacked that one [censored] mayor and Deacon did get hostile. Yeah, attempting to send him elsewhere didn't work. The save just seems to have gotten bugged. How, I may never know. I guess I posted something here with the thought that there was a way to just use the console to "reset" companions or something. That was pretty foolish of me. I figure that the best course of action is just starting another character. At least some things will be fixed that way.
You never stated which mods you're using? True, it's possible they're not related.
Yeah, might be worth going through your mods and seeing if any effect anything related to the companions or NPCs in general?
Also, out of curiosity, do they comment on other things? If you take drugs, run around naked, etc... does any dialogue trigger for that or do they not acknowledge it? Similarly, when modding armor/weapons/power armor in settlements with your companions around, do they comment on it?
Good responses.
I did go through my modlist and 90% of the mods are texture-based and - besides the unique clothing I may give them - don't affect companions at all. Hell, I don't even have any companion make-over mods.
A few others are crafting related. There were two - idle animation alteration mods - that might affect companions...I recall that Deacon stood over a decapitated settler and made a bit of a thoughtful gesture that I had never seen him do before. As peculiar and disturbing as the scene was, perhaps the mod did affect his idle animation as well. I'll go ahead and uninstall it just in case. And there's another overhaul one - Arbitration - that would be the next culprit. It's supposed to alter gameplay related to stealth and combat, including companion AI. Huh. I have my doubts regarding out it may affect non-combat behaviors, but if anything it'd be the cause of Deacon's lapses of apathy during combat. Damn, it feels good finding a lead on one (or more) of these issues. I'll remove it and see.
And in response to your curiosity: weirdly enough the running around naked thing just doesn't trigger any responses. However, drugs and modding do. Sanctuary, where all my companions reside, has become a really annoying place to mod at because of it. At least it's lively.
The idle animation one could be a cause for the dialogue not firing.
From what I can tell, idle animations seem to trigger when companions approach certain areas. Like they will often lean against the wall inbetween the two shops in Good Neighbor. The comments on certain locations or when they talk to NPCs seem to work the same way -- they approach the radius of a certain area and that seems to trigger the lines.
Also interesting that they will still comment on things related to item use.
I'd try removing that one and doing some testing dragging them around!