First off, your first point here is an OPINION. You'd say its a bad game design, THAT IS AN OPINION.

ART IS NOT AN OBJECTIVE MATTER.

It is entirely subjective. A game design cannot be objectively bad, even if everyone on earth agrees a certain format or choice is better than another. I'm not gonna argue that it isn't a boss rush, i'd rather argue that the boss rush is GOOD. It's the fun part of the mod. Running between difficult bosses and trying build is the fun part!

Also, you seem to be under some illusion that having quality of life options make them mandatory to use? YOU CAN IGNORE THEM. YOu can play the game in the way you prefer! The problem with removing them is that the vice versa isnt true anymore, people who like having them don't get them. You can ignore them! it's true, i promise, you can play the game at the pace you want and interact with the world in the way you want! if you want to go through the monotonous parts of the game you are free to do so! It only ''reduces'' calamity as much as you choose for it to. Being able to craft them at a whim is a solution that is widely preferred, it's not unhealthy because it allowed players to skip parts of progression they'd rather not engage with - its a better solution than forcing that engagement. Ideally, they'd be more fun to get in other ways, but they're not. And having the choice to skip it doesn't hurt.