I agree with your overarching point, I just think that there are more pieces of good content than what you listed.It's not horrible, the question is, is it actually good content? Is it interesting to deal with the Hives and locusts, whether you're just stealthrunning past them or fighting them? Is it interesting to delve into 4-5 identical abandoned research centres, kill a gazillion stone statues using the same one trick for your build, and then reading a bunch of loredumps filled with every scifi trope ever?
Todd is fantastic, the Captain and other Aegis folks are very well written, and Underrail's superb underlying systems will support some fun combat scenarios in any given map/encounter. The specific complaint being raised is that when you look at the map/encounter/ quest design of Expeditions areas specifically, they are not very good or fun.
But yes, I think the encounter design is what really fucked this expansion more so than anything. The hives, strongmen, crabs, they were all ass because of the encounter design associated with them. I thought the native invasion was actually a really cool part of the expansion and gave a lot of different ways to explore the enconuter.
I do wish that there was an evil option to do stuff with the natives. I think that it would have added some more depth to the expansion and could have given us an interesting lense to approach the Leumerian ruins considering what we know about the natives after going through Abyssal station.
How it's hinted that the natives are actually the old Leumerians