IIRC, much of these "redefinitions" had to do with abilities and spells which might disrupt a game of gothic horror and mystery. Ravenloft rules didn't make abilities "unreliable", some simply out-and-out didn't work. Things like "Detect Evil". Clerics and paladins got spanked the worst. Since many of these types of abilities and spells have been removed from 4E, this is one area where the rules and the setting are actually more compatible.
Very true, and a more correct assessment of the situation than my original. However, there's another side to this that was starting to rear its head in 3E and would be even more problematic in 4E: the balance concerns of changing any abilities that would have to be changed. In 2E, with a couple exceptions, most of the things changed were spells, so you'd get the surprise once or twice, but typically, a character could swap that spell out for another spell without much long-term impact on play. (Psionics might have proven more of a problem, and I hope that most DMs addressed it by letting PCs know what powers wouldn't work beforehand.) In 4E, though, powers are both integral enough to a PC and few enough that if any power were to prove ill-suited to the setting, you'd really have no choice but to ban it ahead of time, and too much of that might cripple certain classes. It's not insurmontable, any more than a paladin in RL in 2E or 3E, but it's something that a 4E Ravenloft would have to be aware of.
Not much more difficult than hiding the fact that you're 1/3 the size of a human with giant feet. In this regard, any race other than human and, marginally, elves/half-elves would have drawn unwelcome attention, thus limiting the choice of core races suitable for play in all editions. So, nothing changed here.
I don't know; I think dragonborn and tieflings are much more likely to get an extreme response, and harder to pass off as humans that dwarves ("short") or halflings ("children"). (Gnomes, admittedly, have all sorts of troubles.)
I see no incompatibilities with 4E here. Few items doesn't mean no items, and 4E already has an expectation of fewer items per character than earlier editions.
I was getting more at the attitude that "treasure should not be placed for the sake of treasure," which seems to run up against 4E's assumption that campaigns can expect treasure. Still, good adventure design can overcome this.
Here's the irony of all this "documentation" you provided, Matthew: they illustrate how RL is different than the core assumptions and common playstyles of AD&D... the system Ravenloft was designed for! So if you try to hold up these quotes as evidence of why 4E wouldn't fit RL, then they also prove that AD&D wouldn't fit it either, and in some cases, even more so!
Now, obviously this isn't true. Could you run RL with 4E out-of-the-box? No. It would take some tweaking. But that's true of all editions. All of them have been sword-and-sorcery fantasy games, so adaptations need to be made to run a gothic horror game with them. But, as I pointed out above, I think there's at least a couple of areas where 4E is a couple steps ahead of other editions in compatibility.
Yes, Ravenloft and AD&D were always an odd fit--but AD&D was also more amenable to tinkering and reimagining than 4E seems to be at this juncture. Elements of 4E fit Ravenloft very nicely, but I'm not sure if the whole gestalt of the rules set can fit Ravenloft without one or the other shifting, and I'm not convinced that WotC is willing to make the shifts on the rules side.