The problem with Eureka Orthos

[Noumenon]

This "fun" design though was actually a massive game design oversight

It is indeed an oversight, but sometimes the most fun comes from players overcoming these unintended challenges. That's because whereas you are railroaded in doing everything in a specific way or wipe the group in modern Savage and Ultimates, in PotD and HoH there are many ways to tackle the same problem, and no two situations have the same optimal solution. It is probably precisely because of that oversight that make them fun, because the developers are not forcing you to do things a specific way. Unfortunately in Orthos, it looks like they're trying to wrest some control back from players which is why it's a downgrade.

Let's be real. The real reason that PotD is praised so much is because of how much of a hurdle Behemoth was at 180 floors deep losing hours upon hours of progression.

I completely disagree. PotD and HoH are fun because of the necessity of thinking strategically and adjusting your strategy on the fly as I've explained in the OP. Most hardcore DDers actually don't like having to grind early, snoozefest floors, so I'm not sure why you think it's praised because it forces you to lose 8 hours of progression if you make a mistake.