Why the hate with endgame fights?

[Sebazy]

Heck I'm not even saying it always goes up. I actually thought the last few dungeons of ARR (not counting the last 2 from MSQ roulette) had more difficulty than the beginning dungeons of HW, but SB dungeons were definitely more difficult than the beginning ARR and all of the HW ones, and some of the trials are more difficult than others (sync'ed, at least).

That's a fair comment, there are certainly a few dungeons in all tiers that are outliers and that's always going to be a thing with the way SE seem to divvy around the responsibility for designing these dungeons. All 3 expansions have levelling dungeons that will wipe groups if enough people are napping, the problem here isn't so much the difficulty between each expansion's leveling content, it's more that most levelling dungeons are typically more punishing than pretty much any Expert Roulette dungeon after Haukke Manor Hard.

If I did make a picture of the difficulty it would be a whole bunch of small-medium ups and downs and ups and downs along the way, and then the big gigantic jump at the end.

IMHO there's a great big 24 man and expert roulette shaped trough between the little ups and downs and the gigantic jump at the end. This content should be preparing people for EX primals, instead it's just suggesting that they might as well watch Netflix. That's the thing that needs to be addressed imho.