Here's the conclusive demonstration:
The "default effect" (as per
the Wikipedia page that you linked to) is an explanation for why certain options get chosen more than rationality would suggest they warrant. The answer: they are presented as the default, and for various psychological reasons, people err in favour of choosing the default.
But what you are currently trying to explain is the hostility to 4e tieflings. Which has nothing to do with explaining a tendency to choose a default, but rather is all about explaining the vociferous
rejection of a default.
QED.
I think I see your misapprehension.
I raised the default effect specifically to counter the claims that you can simply change the lore at your table and thus the default lore shouldn't matter. That perspective was causing you some confusion, and the default effect helps explain that perspective.
The default lore
does matter. The default effect is part of why the default lore matters.
So if we're in agreement that what the default lore is
does matter (because changing it incurs those various psychological costs and difficulties), it should be pretty easy to see how that creates some vociferous rejection - in this instance, some people weren't very interested in putting forth the effort required to change the default lore back to whatever they liked.
If we agree that the default lore matters to most players, then my raising of the default effect has done it's job: it's shown that canon
matters, and so it should be easily comprehensible that change in the canon isn't an insignificant thing that can easily be written off as "change it if you don't like it."
In 1st ed AD&D brown skin was the default. The colour art you are referring to is, I assume, from the 2nd ed PHB - which thereby changes the canon, without much uproar.
And the tendency of certain people to default to "human being = white" has nothing to do with the "default effect" described on the Wikipedia page that you linked to. But it is closely related to the hostility to halflings with cornrows.
I mean, I can link to articles all day long that show how white people are the default for media representation, but I think that'd be a bit of a distraction here. The thrust of my point is that there are potentially a lot of different reasons why the change form 1e brown skin to 2e ruddy cheeks might not be as big a deal as the change from variable tieflings to One True Tiefling, or the change in mind flayer lore from the DSG might not be as big a deal as the change in Strahd's backstory for
Curse of Strahd. One can't simply point to the times that an outcry
doesn't result from a lore change as evidence that lore changes in general shouldn't cause an outcry, because the circumstances are different for each change and each individual asked to accept the change. And this would be something that if I were WotC, I'd be very interested in analyzing.
This is all just elaboration of my point that tieflings were a particular flashpoing. And has nothing to do with any "default effect".
The default effect is what's causing the "flashpoint."
People asked to change from the default assumptions of the game to tell the stories they want to tell incurs in them a new psychological cost that they may reject having to pay (if not over one change, than over another, or just over the course of many).
If you want to understand the anger over new canon, understanding why people choose the default is an important element of that.