Yes, in fact, I always assumed the derogatory nature of the term (McX for X = mansion) is a dig at wanting an impressive-looking facade, but not being able to pay for a larger plot of land or the architect to design that big facade.
To me, "McX" evokes the image of fast food. Something bland, unappealing, and one-size-fits-all that sacrifices quality for mass production.
The later McMansions may have evolved as a response to the perception of them being generic by slapping on superficial and poorly designed accents. It doesn't change the low quality. Burger King isn't considered any better than McDonalds just because you can "have it your way".
But mostly it's about the houses being unnecessarily large. Now that I think about it, the McDonalds metaphor here is probably meant to be that they're Super-Sized houses.
Well of course it has to do with money, what you are referring to would increase the property cost by 2-3x. The same house but custom built home on an acre of land in the city in the u.s. east would run you $1million+, or have a prefab home on .3 acres (subdivision) for $400,000.
