The Financial Times suggests there is one primary reason more Chinese homebuyers are choosing McMansions: they are status symbols. One note: the McMansions hinted at in this article sound opulent beyond the average American McMansion.
Critics of McMansions would often argue a similar process is at work in the United States: McMansion owners want to impress others with their large house. While the price is not so much of an issue (much smaller pieces of real estate in desirable locations can cost much more), the homes show off through an impressive/ostentatious front, plenty of interior space, nice furnishings, and lots of stuff. On the other hand, I suspect a good number of owners purchased such homes because they say they need the space or got a good deal or liked the amenities of the home and neighborhood.
I’m not sure these are mutually exclusive arguments. Homebuyers can want a suburban experience and want to do it in a home that broadcasts their success. After all, the suburban single-family home represents middle- or upper-class success as well as expressions of individualism.