The problem is that every opinion about a content is subjective. Maybe not if there are bugs involved but what exactly counts as broken otherwise? If the content function, can it really be broken in a objective way? For me that is not the case. Eureka for example is not broken imo. Its just content that probably a lot of people find boring but you can still do it. Thus why the fun part comes into this. I mean we are not even saying that fun should be the only reasonable way to judge something but its a very good indicator if you have successful content or not. Because if its death by arrival it seems to not have been fun for a lot of people thus there is something wrong with this kind of content.
I dont find Eureka fun thus I go "I dislike it because x reasons" but these reasons are created by my own definition of fun. Thus other might find it fun and see nothing wrong with it and since its functioning then its also not broken. So how then would you argue against such content if you dont like it? Also nobody is saying that just because something is not fun for someone that it should be put out of the game. But there is a problem if a big part of the playerbase does not like new content or that they create something that does not live long enough. Thats two very different points. And at least for me this game just lacks content that can be enjoyed by a great majority of the playerbase for a longer time. If its fun or not is individually, my problem is that there does not exist much of them ingame at all and too much specific content for smaller groups.
Also it feels like you want to try and use a lot of objective views in a discussion but as soon as we go beyond simple numbers which can count as facts, we are going into the subjective part of it.