I agree to some extent. However, PON had many, if not most, of its story arcs concluded in TTT. There were questions to be asked, surely, but the main conflict was resolved. That could have been the case for TAE, if not for all of the questions raised by the cliffhanger ending. Looking at Goodreads reviews, it seems that many people aren't even aware that there will be a third series.
Was it really that different?
Moenghus was a huge build up - dies suddenly
Cnaiur - no idea if he lived or died
Akka - denounces Kellhus and walks off - major cliff hanger
Esmenet - still torn between Kellhus and Akka
Kellhus - Master of the Three Seas - ok this one is pretty much 'concluded', but what's next?
Iyokus and the Ciphrang?
Consult?
Inchoroi?
What the heck is TTT?
What's the No God?
We still know nothing of the Nonmen, what's up with them?
Which other ones am I missing? Depending on which themantic elements you choose to look at, we really didn't get a whole lot from TTT. It ends as much in the middle of the story that TUC does.
As per "main conflict resolved" in TUC that you noted above:
Resolved Kellhus - dead
Resolved Consult - usurped and replaced
Resolved Kelmomas - NG
Resolved Esment - done
Resolved Mimara and her pregnancy - finished
Resolved Serwe - gone
Resolved TGO - its dead
Everything is as resolved or as unresolved as you choose to view it - and thats the point, isn't it? I can't speak to your frame of mind when originally reading TTT vs TUC, but if you are viewing them from the same lens now, how different are they?
We have the benefit of 4 books after TTT, not to mention the better part of a decade of speculation and conversation to make sense of it. Comparing what we know of TTT now compared to what we know of TUC now is hardly an apples to apples comparison is it? And how can we go back, and remember how we felt about TTT back then and fairly compare it to TUC now? Even if you read them all at once very recently, you still have 4 books between them, and trying to remember would be revisionist at best, yeah?