Such 'tricks' are of course, not to be underestimated. It doesn't push the plot forward - in terms of events happening - but it does serve to put these events into context.
In this particular case it shows two people having a casual conversation about something completely trivial on their way to brutally murder a group of people.
It shows what kind of characters they are.
RPG games always revolve around a particular character - or a group of characters.
So even if events are secondary (old dungeon crawlers have no plot) in RPGs, such little tricks are crucial.
I wouldn't call them tricks, necessarily. Frankly, in a videogame I think expositional elements serve an interesting role that you don't see in other media. Namely, it gives the player more control over the pacing of the game. Considering that these are generally optional, it allows the player to take a break from the rest of the gameplay, or modify the tension in the game. While still technically "playing" the game (and that's usually a good thing in game design...)
Like in GTA, for example - I'm never going to "have" to hang out and watch television. But if I've been stuck on a particular mission, and just need to relax a bit, it helps to break up the tension a bit and keep things from getting repetitive. All while serving the role of pulling the player further into the game fiction. Or the little conversations that go on while I'm driving an NPC to a mission segment - it's really just there to keep the player from getting too bored; but it helps transform what would otherwise be just another drive to a map point into something a lot more interesting. And all without necessitating yet another cut-scene.
In The Elder Scrolls, I'd obsessively collect as many book collections as I could. I wouldn't read every single one as soon as I picked them up, but a lot of times when I'd get back from a dungeon run it'd be a nice break to hang out and read a couple and dig further into the game's lore before I decided to head back again. It's all up to the player how much and when they want to explore this sort of thing. Even in Fallout 3, I wouldn't always read every single terminal I came across, but they'd usually download into my Pip-Boy so I could go back and check them out later. Because sometimes you want to just keeping playing the game, and other times you just want to hang out in the game for a little bit; or just need to take a break from the action a little bit.
I think that's a really important element in a game. Because you can't use the same tricks for breaking the tension, comedic relief, etc, that you can in other media. When the tension gets too high, or starts to become repetitive; the player will decide when to take a break. Without some potential expositional elements, or background info - they're going to turn off the game. And that always means they might put some other game in the drive the next time.