I’m not sure there is anything objectively bad about these designs. Does it affect the utility of the house? Or is there some inherent ugliness that comes with affordable and popular things?
They're generally very large and of low-quality construction, making them expensive to heat, cool, and maintain, for little upside. They're also generally kind of impractical; you end up with either way too many rooms, or impractically _big_ rooms.
There's an element of subjectivity to the aesthetics, obviously, but I don't think you'll find many people who'll see most of the examples on that site and go "that looks good actually".
I would question both of these adjectives, where I live, "affordable" is sub-400'000 USD and "popular" is a 3-bedroom terraced house. I would use expensive and extravagant instead.
General consensus on definition seems to be "very large house, not designed by an architect, cheap construction". So they are both expensive (because they're really, really big) but also, well, cheaper than something that big done properly.
On the 'elite upbringing' thing, well, ever seen photos of the interiors of Donald Trump's houses? An elite upbringing does not necessarily imply taste.