There are two flavors of nostalgia; I call them the upward kind and the downward kind. To be nostalgic for the better things in the past that we have lost now is upward, to be nostalgic for the worse things (worse, as in "crude" and "incompetent", not "morally vile") in the past that we have grown out of is downward. For example, people today never came up with computer case designs as stylish as Silicon Graphics; be nostalgic about this is upward. (NOTE: nostalgia being "upward" and "downward" does not mean it's "good" or "bad"; these two words merely refers to the quality of the subject. There isn't (and shouldn't be) any moral judgement.)
While whether certain things have been better or worse is largely subjective, some things definitely fall into the downward category. Such things are common especially in Mainland China (because we almost never have nice enough things in the past 40 years); a lot of people selling crude candies and toys and consumer electronics and et cetera labling them "80后" "90后" (lit. "after 80" "after 90"; people born between 1980~1989 and 1990~1999) on Taobao (Aliexpress but China. But the company behind Aliexpress do be a Chinese company, so it really is the other way around), and they were never as cool as I wish it could be.
I was never a kid who likes Chinese culture that much. To me, nostalgia almost exclusively means classic western style, and one of the big questions I think about a lot in my childhood is "Why we couldn't live our lives like the foreigners I saw on TV", probably due to how my family almost exclusively watches Hongkong and foreign TV shows with subtitles. Oh how I wish to look at the beautiful buildings on the Shamian Island again, even if the peace of mind it will bring me are painfully ephemeral.