Recently I did another run of the game and decided to choose the hunter class, and it turns out that using a bow marginalises the whole fight, so there's also that.
To me the 2nd chapter was amazing, apart from the fact you have to travel tens of thousands of blocks, I get why the parkour can be annoying, it's too long, but the checkpoints make it manageable, as for the fight, again bow makes it way too easy.
While I do agree with that, I'd much prefer if the difficulty of the story would gradually increase so that you could progress both at the same time.
As Echo Weaver said, once you die in that fight, you have to either give up all your gear you've brought there or just bang your head against a wall, and since you've probably brought your best stuff to the fight, you don't want to lose it.
True, but if you have to drop into a hole, and expect a boss down there, you would bring your best gear there, and jump in difficulty from exploring the Archives and fighting Eidolon is quite big in my opinion.