SE explained why they did it this way. In summary, they didn't think it through. They just did it like Eureka because they were in a rush, and didn't even so much as discuss it with Yoshi-P. This seems to explain "the formula" in general. They just do "what they did last time" because they don't feel like they have time to think about it, or to make their job smooth and consistent.

They actually solved it by making it so you can queue into your own instance of Occult Crescent that is just for that Forked Tower alliance, at least at first, and after a bit others will likely get into the instance. They are going to make a normal mode version next time.

They didn't intend it to be quite as difficult as it is and you can actually kind of see that with things like the telegraphing and the cast names. That was the whole reason for having 3 chances, so that it's not 1 mistake and over. What I suppose they didn't anticipate was that many of those "mistakes" may be caused by large-scale wipes caused by a single mistake like misplaced stacks, mines, etc.