The need to take Heroes on certain Elonian missions is really not fair in hard mode. Remember that it is said by Anet that "You can use Heroes and Hench in hard mode but we don't guarantee success."
Since success with Heroes is not guaranteed in hard mode, that makes it totally unfair to be forced to use Heroes in hard mode in Nightfall missions that require them.
For example, on Jokanur Diggings being forced to take Melonni is a really weak link in that party already. Then if the player character is a Dervish himself, he is forced to have his party pigeonholed into an extremely weak setup of 50% of his 4 man party being limited to the Dervish class. This is an untenable situation in hard mode, and unbalances the game against the Dervish player for that mission in hard mode.
The other thing is that NPC allies who must survive need to be given flags like Heroes/Hench have. Ie: Kormir, Rurik, Mhenlo, Togo etc. etc. It's completely unfair to lose missions due to not being able to control their often-ridiculous Leeroy behaviour. In Jokanur Diggings Kormir even attacks the Sunspear ghosts that she is not supposed to according to the bonus objective, and there is no way to make her stop. I was busy frantically complaining at my allies to stop hitting the Sunspear ghost, only to then realize that it was Kormir doing it! The resulting confusion led me to dragging Kormir away as fast as I could before the bonus ghost got killed by Kormir, but my party didn't follow in time and hence we all got wiped a few seconds later. Mission failures for reasons like these should not happen. Likewise Kormir is never ever able to stop aggroing anything, even when it's time to retreat because the whole party is about to die. Kormir will be lagging behind the retreating party, getting killed thus causing mission failure for the whole party. Hard mode is supposed to be based on a player's skill at the game, not a player's luck at avoiding having the NPC ally cause mission failure for a dumb reason. Giving NPC allies flags would make hard mode be much more fair and balanced.
N

Melonni sucks (thankgod we don't have to use Zenmai anywhere).