As someone whose group is listed in the playtester credits for both HotDQ and RoT and saw the first hand changes from the very beginning - there is a reason RoT is much better off than HotDQ, and that is because the game changed significantly in terms of base math and the abilities of PCs as well as monsters throughout the playtest. I give KP a bit of a pass on this one, because very basic mechanics were changed throughout the playtest of HotDQ.
Also, thank the lords they changed some of those episodes; episode 3 was much rougher when we went through it.
EDIT: Hilariously, one of the WotC changes to NPCs made the first episode TPK-ville until KP got around to revising the monsters used. I remember being in the middle of the episode and then getting the new monster changes and being like "Wait, WHAT?? Uh, ok?". Was actually pretty funny after the fact.
You might be misunderstanding my point.
If the Paladin no longer has his Whizbang power, how does that change the module in any way?
If Kobolds suddenly have pack tactics instead of having multiple spear throws, how does that change the module in any way?
Yes, if all monsters are slightly stronger after playtesting determines that they are all wimps and Greenest is filled with wimpy monsters to begin with, yes the designers have to go off and lower each encounter by a monster or yank some encounters in Greenest or add some more healing potions. Some adjustments would have to be made. We all understand that.
But, D&D has been around for 40 years. Experienced DMs know the difference between good module design and bad, even if there are some disagreements with DMs as to whether this module is bad or not. It's like a Marvel movie on Rotten Tomatoes. Everyone is expecting at least an 85%. HotDQ is getting a 50% (or whatever) on Rotten Tomatoes where a significant percentage like it and a significant percentage do not.
HotDQ is like the first Marvel movie and everyone was expecting this wonderful flagship of an adventure and it fell on its face quite a bit. Perception type abilities and stealth like abilities have been around for decades. If they changed a little bit from playtest, it shouldn't suddenly make the adventure go from good to bad.
What made the adventure bad was stuff that was built in. Like going to a town when a dragon is attacking it. Super heroic self sacrificing PCs might do that, but many PCs have different motivations and that's like asking them to jump off a cliff without a parachute.
Although there are people who disagree with me, the Half Dragon encounter is a terrible encounter and the very definition of railroady. Yes, three things can happen: a local can die, a PC can take a dirt nap (unless the DM doesn't really pull the trigger), or all of the PCs can fight and some or all of them can take a dirt nap (again,unless the DM doesn't really pull the trigger), but all of those choices suck and I don't play the game to be given sucky choices. I don't play the game for the game designers to teach me lessons. I play the game to have fun. It's a game.
For this to be the flagship adventure, it should definitely been much better designed and sorry, but the things that I do not like about the module have nothing to do with game mechanics. To me, that an excuse.