Most denizens, I suspect, probably feel that something is not quite right but couldn't put their finger on it quickly enough to stop their purchase or possibly more cynically, don't care until they flip the house.
If you look at these, you'll notice something: they're by and large consistent within themselves and the author of that piece is often (and I say "often" because it's a pop piece) able to tell you what aspects the architects of that style are focusing on. Any given style of architecture might not be your thing, but I bet that you can see commonalities of design within a given design family. In particular it's worth looking at horizontal lines (stories of a house); it's sometimes fashionable for different stories of a house to differ stylistically, but do different parts of the house, including the roof, differ notably on that horizontal line?
One of the deadest giveaways as to whether you can reasonably call it a "McMansion": look at the windows. Some of the houses on McMansion Hell have six different styles of window on the same story of the house. Sometimes they just look plastered on, like the house was built and somebody said "let's add a window there". It's not just bad taste, which has a lot of variance--it's also incoherence, and while there is some taste in evaluating whether various elements that a design adopts cohere together, there's a reasonable-person test there that doesn't really exist for like-it/don't-like-it. McMansions like the ones under discussion are incoherent because they're not designed for coherence, they're designed to tick off boxes in a "How To Increase The Value Of The Thing You're Flipping" checklist. (Few McMansions are built by the owners.) They're zits on a good neighborhood.
Ever heard the adage, learn the rules in order to break them? An analogy that I like is with regard to painting: a cubist Picasso and realist Courbet are both technically masterful and appealing works, but if you mash them together the point becomes that they don't work together at all. And that can be fine--maybe the point of what you're doing is to highlight that discordance--but if you do it without understanding how and why they work, you're just creating a trainwreck.
[1] https://www.engadget.com/2017/03/07/apis-cor-3d-printed-hous...
* No clear architectural style, or a haphazard/incoherent mix of styles
* Brick or stone facades in front, and cheap siding on the (less visible) sides
* Non-structural arches and columns
* Oddly placed/sized windows
* Multiple roof lines, chimneys and dormers
To the extent that a "Recently built house in a more or less modern style" incorporates these elements, it can be considered more or less a McMansion.
Isn't that just a new style?
The point is, with the effort and money spent, the houses are not even necessarily nice to live in when the designer just adds a hodge podge of features. The critique may sound elitist but the actual defects are concrete once you notice them and not just 'accept and adapt' to them.
Do they, though? Maybe they're completely happy with their houses and we're just assuming the grapes are sour.
A lot of time on HN is spent mocking "gamer aesthetic" on hardware the commenter would have otherwise actually liked to use. Garish LED-lighting, bulky-looks and oblique angles aren't my thing either, but HN loves to complain about McKeyboards, McHeadphones, McLaptops and McCases.
"Gamer aesthetic" and "McMansion aethetic" are valid phenomena and people have the right to critique those tastes without invoking classism, despite the sense of superiorioty occasionally found in the consumers of both.