He should have listened. The number one reason for me not playing (and not buying) certain games is because I find them too difficult at key points and would rather just pass on the frustration.
We did listen to Adam.
In this thread (or perhaps another), I threw Adam under the wheels of the difficulty cart because he built a water genasi 10 fighter / 7 cleric as his starting character. Genasi are not a powerhouse race, but more importantly, being able to cast only 4th level cleric spells in an 18th level dungeon is practically like being able to cast no cleric spells at all. Low on feats, high on nothing, the character is just flat out bad.
Adam's a smart guy, and he is lightly familiar with D&D. So how should we tune an expansion that's oriented around 20th+ level characters? When I played through the expansion the first time, long stretches were so trivially easy that I became bored. I enjoyed the story and the areas a lot, but the overall low level of difficulty probably would have made me stop playing the game if it hadn't been an Obsidian product.
Kevin and Avellone and Ferg were quick to prevent me from requesting IWD2-levels of difficulty because they have more sympathy for nubs than I do. And I should make it clear that I didn't tune the combat personally. I made suggestions that were considered by individual designers and either accepted, rejected, or modified based on their best judgment and the goals Kevin thought were appropriate. I think the game difficulty, as tuned by the designers, is interesting but not difficult for me. And by Adam's experience, some parts are very difficult for someone with his relatively-low familiarity with D&D. D&D is a complicated ruleset and there's a minimum level of understanding required to do anything with it -- especially at 20th+ level. The only real way to get around that is to selectively shave off so much of the complex D&D rules that you're left with something like BG: Dark Alliance or the old Capcom D&D games. If you try to keep all of the core rules but tune the difficulty so you don't really have to know anything, the D&D veterans simply aren't going to find the gameplay compelling at all.
For the record, I will also say that the Black Hound will not be tuned in this way. While I am changing a bunch of rules for the campaign, combat babies will have to leave their rattles and bonnets at the door.