It doesn't appear that Antoni Gaudí had anything to do with the etymology of the term "gaudy" as it was in use hundreds of years before he was born.

https://en.wiktionary.org/wiki/gaudy https://www.merriam-webster.com/dictionary/gaudy

I couldn't help looking it up because the idea that a single artist could stand out so much to be singularly associated with that term was tempting. I expect that is why such a false association persists.

Also:

50's US cars were also exceedingly well built using high quality materials and mostly/nearly by hand..

which goes against the 'cheap / phony materials' ethos critiqued in mcmansions..

that said, plenty of people I'm sure critiqued the 'chintzy' 50s asthetic and increased use of plastics in the day..

I'm no designer either, but I think Caddy fins were great examples of baroque flourishes -- excessive extensions to past design motifs that give a heightened sense of motion or flow or accent. Future designs can't build on such flourishes. They were stylistic endpoints, like the accents in Art Deco, but often use a coherent set of design principles within a time period and thus create a harmony of their own.

But McMansions lack common flourishes or motifs. They share only size and a brutal ostentation intended only to say, "I have money, and taste be damned."

The best exposition I know on the suburban blight AKA McMansions is "The Geography of Nowhere" by James Howard Kunstler.