No matter what any dev does, short of making them unbeatable there will always be someone complaining that enemies or NMs or bosses are "too easy." Hell, even with that Pandemonium Warden fiasco in FFXI a few years back I saw people blaming the players, rather than the devs, for the fight taking 18 hours. It's good game design to make fights that are challenging for most players, but also feasible for most players to beat. This maximizes the content that's doable for the playerbase for the amount of manhours that go into making these NMs, which is something the dev team is in very short supply of right now.

tl:dr Dev team can't waste time making content for 5% of the playerbase like a lot of FFXI's endgame content, it needs to be accessible to more people. If they can make a hard mode or something for more drops in instanced content, then that'd work fine for everyone I think.