I'm not sure I understand where the distinction is between "Having this in the game is emotionally harmful" to me and "I just don't care for that". when it comes to lines. Or maybe there is no distinction?
Well, that depends on how you want to relate to your players.
One way to look at a line is, "This will ruin my night." Sometimes, knowing exaclty how can be helpful, but overall... do you care if you ruin a player's night?