Nostalgia didn't always have a positive tone. In fact, before the 20th century, the word was used in the pejorative sense.
Nostalgia in those days was a technical term used and discussed primarily by specialists. In the twentieth century, however, the word has become fully demedicalized. It now means little more than a sentimental attachment to a lost or past era, a fuzzy feeling about a soft-focus earlier time, and is more often used of an advertising campaign, a film or a memory of childhood than with regard to any strong sense of its etymology, “pain about homecoming”.
Today, people use the word nostalgia to look back on happier times, perhaps a slower one.
Nostalgia seems now to mark out a particular type of attention. If you call something “nostalgic”, you are suggesting that it evokes a memory of a former pleasure, a bitter-sweet recognition of the passing of time, or a sense of a lost era. To be nostalgic oneself is to experience those (possibly quietly melancholic) pleasures. It would be odd, indeed insulting, to describe the return of a concentration camp victim to Auschwitz as nostalgic.
Fantasizing about a simpler, pre-Internet world is a nostalgic reaction to rapid digital change. We're all stuck in the whirlwind of 24/7 breaking news on social media that makes everything feel so immediate we can't prioritize the important.
We can't even appreciate the moment. The present is quickly consumed and forgotten. The next iteration of nostalgia may become synonymous with experience, a world that was devoid of distorted facts and where events meant something.