Might your impression of these pictures be colored by your life experience during that time, ie. you might have been in your early twenties with the iPhone 4, and those pictures carried the smell of that time in your life.

That's entirely possible and quite likely. The only way to find out would be to renovate the battery and take it out to go shoot stuff. I'm not sure I'm that invested to make the effort especially as the rest of the handset is basically useless at this point.