Earlier quoted context omitted.
So size is the most critical aspect of significance?
Excellent observation. Most critical? Maybe not. But it is undoubtedly very much a significant and underrecognized factor. The Overview Effect is a real thing: https://en.wikipedia.org/wiki/Overview_effect
At its best, it inspires calls to environmentalism (the fragility of the Earth), but at its worst, and it's usually at its worst, it inspires nihilistic Carl Saganisms like the Pale Blue Dot.