Which inspired me to think of this way; why is the genre called “slice-of-life”?
Sure, it usually attempts to present characters in a daily life based setting, but usually they can lean to more fantastical (Kino no Tabi, Mushishi) or sci-fi-ish (ARIA, YKK) bents.
In fact, the Japanese term for these types of shows are “kuuki-kei“, that roughly translates to “atmosphere/ambience-type”, and that term is really quite spot-on as a term describing those types of shows.
So why don’t we all just call it “ambience” anime? It’s much more accurate and a better term to describe them than “slice-of-life”; which in most cases, usually isn’t quite correct for most of them. Truly, their selling points are the settings and the pull they have towards the viewers, rather than the characters or the plotlines.