Author could've just called it cutification without wasting a paragraph to explain a common loanword. It's not like these trends actually come from Japan. Look at some of these top 20 Japanese sites[0], none of them look like what the author's describing.
The author is probably referring to a general trend in Japan where simple, cute, slice of life ambience is becoming very popular in various media like video games and anime.
The general trend of Kawaii things also looks nothing like the websites he's talking about. For example, they lack the distinctive hand-drawn cartoon art style like this site has[0].