I don't like BFA 5mans. I think part of it is that the themes don't feel like part of the WoW universe. The original WoW classes were humans, gnomes, dwarves, night elves, orcs, trolls, tauren, and undead. Only THREE of those really get represented in the BFA 5 mans in humans, trolls and gnomes (and humans are probably the most boring one at this point). It feels like when it comes to 5 mans, over half the lore is sitting it out.
The other part is I don't care about the lore behind them at all. Has anyone ever really said "OMG I am fighting Gorak Tul!!!!" or "OMG I am fighting Harlan Sweete!!!" Nope. These are forgettable bland characters.