There is some location specific banter - however it is not realistic to have too many scripted lines in a game that is essentially open world. There are several paths to numerous objectives and it's rather hard to guarantee that banter would trigger at the right time and situation for all players. You would have to code in so many different variables. If your banter is bugged, I understand the desire to have an option of manually triggering it, but at this point it isn't a solution because the majority of players don't really have issues.
But this game is nothing like DA:O or DA2. They changed the system because the entire game changed quite a bit. Most areas are very open now, much, much less linear corridors like in the previous titles. If you make the game more open-world, allowing the player to take different paths to various objectives and such, you make it much harder to script anything.
Triggering a forced banter after clearing rifts doesn't make a whole lot of sense unless the banter is related to the rift or something. Most banter is casual chatting between the party members, as such it is meant to appear seemingly randomly, not triggered by anything specific. Which the system does try to do. Walking out of a camp is also a bit too specific. The banter really needs to be completely random when exploring most of the time.
I do think that they should apply a minimum-maximum time period of no banter. Keep the banter random, but if it hasn't triggered in lets say 45 minutes, it will do so automatically no matter what. If it is interrupted, it will repeat at the next opportunity. And let's say you can't get it more often than 3-4x in an hour.
Same with music. Keep the element of randomness, but apply some harsh limitations to avoid extreme variations that are inevitable with a too random approach. If the RNG bugs out there should still be hard-coded instructions for the game to either cut all banter/music or force it no matter what.
------
Personally I have had some issues, but nothing consistent. I get plenty of banter and a good deal of music, however there are periods of long silence as-well. I haven't clocked anything but I do believe that the game doesn't exactly handle every situation perfectly. I usually keep the game open for 16+ hours a day as I play in windowed mode and I just don't see much point in closing it for any reason other than to shut the PC off for the night. I do think that this extended period can cause some bugginess, but that's just a speculation.
I've had a few cases of non-stop repeating banter which shouldn't ever happen, but it does. For example Dorian and Varric making bets on whether or not I beat Coryphicus. Pretty much happened every 5 minutes in the Forgotten Oasis. Perhaps the reason was that this is one of the few banters where you actually get the option to say something yourself. Maybe the game doesn't stop until you've tried all three replies... still, doesn't make any sense to keep repeating it.
Also, the party's reaction to Dragon Fights seems to be a bit weak. Bull got excited a few times, and a few others made a single comment here and there, but in general, nobody said anything. Which is kinda weak. I would have at-least expected Cassandra to have more lines, considering that she is an accomplished Dragon Hunter after all, from a line of dragon hunters no less.
But in general I'm pretty happy with the party interactions. I loved how Dorian and Bull actually started dating and discussing their sex life during banter, lol. And that I later got to ask them both about it in Skyhold and had more lines about it. That's very good, makes the party seem very dynamic and evolving.
It is understandable that for a game of this immense size, that includes dozens and dozens of hours of basically walking around in wilderness, it's not easy to keep the banter going in a manner that please everyone.
I do hope they try to improve it of-course. Always ways to improve things and with the popularity and success of the title, I would expect a long term commitment from the Devs to keep the patches and DLC-s coming.