NMs were never end-game.

Yoshida said dungeons and raid content are aimed at mid-high level players (note still not end-game.)

If they add dynamic NM fights like other MMOs people will complain when the cap raises that the boss gets easier.

Lower the party number didn't make NMs easier.

Humans love to find scapegoats so when something is changed, updated or removed people pay closer attention than they used to to find something wrong.

"Making a game easy" will attract everyone, why do you think Farmville and WoW were the most popular western online games? Long gone are the days where people actually like and want challenge in their video games.

If they add a boss rush NM like Pandemonium Ward in XI, people will be retarded and fight it for 18 hours then blame SE, this is partially why they've moved to the "light side" of things, because you throw a challenge, people don't know when to give up; Example, in PW, they put a 2-3 hour cap on the fight and it will despawn, yet the only other adjustment they did, was removed some of it's forms but didn't adjust its power nor lamp spawns which proves the group of players who fought till they got sick were just being stupid about fighting that long because people are killing it just fine with its 3 hour time limit.

They want to prevent situations like that from happening again.