While I get your point, your examples are a bit off. Scandenavian heritage is filled by the Northlanders (but essentially stereotypical Vikings with boats, horned helms and the like), Cetlic heritage is purely the realm of the Moonshaes and Ffolk, which is based on Ireland so hard it hurts. Slavic heritage isn't Ravenloft (although Barovia is little but a repurposed Transylvania) but areas like Narfell and Damara, and the Romani analogue in Faerun is the Gur (although Ravenloft's Vistani are likewise based on the Gypsy stereotype). Tack on that Amn is essentially Moorish/occupied Spain, Chessenta is Greece, and Mulhorand is Egypt and you have a huge melting pot of tropes running around. (and that ignores Maztica, Kara-Tur, and Zakhara).
I guess the better question is... what would work better?
D&D sourcebooks, even in the height of production, were finite as far as how much detail a culture could get. Its far easier to describe a setting like "Its Ancient Egypt with magic" or "Its pirates of the Caribbean without firearms" and rely on the tropes, stereotypes, and generalizations those phrases associate than explain every nuance of a fantasy culture (which will inevitably be a reskinning of an existing culture anyway since humans can only visualize that which they are already familiar with. I mean, we can't even give non-humans cultures that don't invariably end up some variant on human culture, its nearly impossible to do that with humans.
Now, I'm not saying we can't be sensitive to cultural depictions of how a race/culture is depicted, but at a certain point we have to determine if having Barovia be an accurate depiction of Medieval Slavic and Romani culture is worth giving up "Transylvania as depicted by Universal/Hammer films".