Imo trash before a boss adds to the immersion and story. However, I'd argue that corpse runs after a wipe don't. I never minded them in WoW, though, except in some extreme cases. Almost only running raids with friends or my guild, there was always something going on - either talking about some boss mechanics in more depth or sharing ideas, or just joking around.
@ topic: There are two very small things that are usually not mentioned about the good parts of the game (at least I haven't seen it yet).
First, I like that the gear quality actually means something, at least at the lower levels. I got my first blue items yesterday from finishing the miner / botanist ARR storylines. My main gear is still completely white/grey, with I think one pink. Instances drop some greens now and then. No idea if the endgame is again "everything is always full purple and only ilvl differs" like in WoW, though, which I never liked. Though that's as said just a minor pet peeve.
Second (though very personal), it seems super common to just give the healer the player commendations in leveling dungeons, no matter what. I'm doing most instances as healer, so that's usually me.