The OP has many legit points.
The biggest issue I have with this game is its QA problems. Being a small studio, Owlcat has really suffered from issues like bugs and lack of consideration for user experience.
For example, even till this day, the game still has some items whose special effects do not work. Nature's Wrath trident (sold by Issil at HATEOT) does not proc lightning vulnerability on hit. Black Star starknife is supposed to proc EITHER crushing despair, slay living OR confusion (one of them) on crit, yet in game when crit it procs all three at the same time, and the slay living ability forces the player to choose a target just like active casting, which basically uses up the next round. It is a good thing that the devs are still working hard to fix these bugs though.
Another example is the complete mess in character building UI - compare this to POE 2 for example, or every other RPG game. What players need is a clear screen where skills / talents and their effects (in terms of stats change and special effects) are clearly shown in the same page in a wholistic manner. This is not implemented in PFK. One has to maintain a speadsheet outside the game in order to keep track of all the feats / BAB etc because when building the character, he's blocked off from seeing which feats he can pick vs their effects, quite unnecessarily due to implementation oversight.
Some game design features should have been more thoughtful. For example in Kingdom Management, as many have rightly pointed out, many buildings are completely useless. Why do we still have them in the game? The biggest reward is from upgrading your kingdom stats and get masterpiece related objectives completely done asap. From very early on, this set of "real objectives" encourage intentional stalling as the only viable tactic if one is on Hard or higher difficulties, because each masterpiece can be quite crucial to the end game. In my playthroughs, I try to stall chapter advancement as much as possible, just to rank up kingdom stats and roll more artisan gifts. This takes up a few hours of play time every chapter, and is a boring chore no one really enjoys.
However on the other hand, a lot of efforts have been poured into the game by the devs - it has rich and complex contents, be it main plot or side quests. Boss designs are great. So are items and skills.
Truth be told, to this day the game is still kind of in a "diamond in the rough" state. Just think about this: in Steam Global Achievement ladder only 0.7% of players have beaten the "real" ending of Tenebrous Depths. Less than 1%. Many many players have been discouraged by all these issues which unnecessarily stopped them from enjoying the game in its completeness. How many could have asked for refund / told their friends not to play it? It is a pitty.