Just because the game is "party-based, class-based, 2D-isometric, sprawling, richly written, fantasy RTwP game inspired by the Infinity Engine" does not mean it will be good. So concerns about mechanics, gameplay, bugs etc. are a legitimate concerns.
If PoE will fall flat then we will never get a good game like that in a long time.
I genuinely feel your concern about this game falling flat is a misnomer. There is a proven audience here that love these old school games and games of a similar ilk that harken back to those good old days. With that in mind, you will have people who will just go out and buy the game regardless of what features the game provides. I understand that people want to make the game as good as possible, but within game development you have to reach a point where you say, "That's it guys, this is the game we are making in all it's splendor!" and any other features that were considered borderline unfortunately get binned or put on hold to be discussed at a later date.
It wouldn't surprise me that most of the feedback with bugs and inconsistencies with the old IE games they are getting, they already know about and have fixes in the pipeline waiting to go in the release candidate, or they may already be in the internal build being tested as of this minute.
Ultimately, they know what they are providing and are good for it, just have a little faith that the game they are making will be good even though it doesn't feel as if it's progressive enough for you. Sometimes, just being old fashioned breathes a breath of fresh air into a stagnate genre where its all action focused(Not saying that I hate aRPGs but there are loads of them around and some pretty awesome ones coming out in the next 6 months).
Also, as a side note; After World of Warcraft hit, countless copycat MMOs came out that tried to piggyback on its sucess. Copying alot of its mechanics, look and feel, quest design, loot allocation etc. Copying that game didn't make the copies any less successful, just no where near the success that WoW was.
Reinventing the wheel each time is not always feasible when you could learn from the past and bring back a design that was beloved and worked for the game you were creating.