People are discussing it because they don't understand it. "For fun" is not a good argument, some people nail their genitals to wooden desk for fun. That doesn't help me understand what's happening in their brain.
Comparing BG and other games to ganking low lvl players in WoW makes no sense at all. If you are playing BG, MOBA etc. you WANT to fight other players and even if you are getting smashed, you can still fight back and do some objectives - splitpush, destroy towers, take points etc. However if you are low lvl in WoW peacefully leveling you DON'T WANT to fight other players and most importantly you CAN'T fight back or do anything. It's completely different thing.
Funny thing is that a lot of people mention that they are doing it out of boredom and then say something like "maybe this game is not for you" or "do something else". But it works other way around, you know. If you are so bored with WoW, maybe it's not game for you and you should try something else. Or somebody force you to play WoW?