Great thread and topic. This is something I've been thinking more and more about. I've personally been shooting film since I was about 16 (27 now) and I'm beginning to realize that for the past 11 years I've been focusing so much on art photography despite some of my casual "snapshots" being my most dear photographs.
Think "Vivian Meyer." One never knows what may become of their images. Many may never care......some may care a little......a few may care a lot.
As it has been said, "A faith, a truth, a generation of men die, and are forgotten, and it does not matter, except, perhaps, to the few of those who professed the faith, believed the truth, or loved the men."
I'm currently going through my old negatives, 10 fat folders of them with a view to putting them in printed books. Currently scanning, spotting and tweaking 1975 - 1980 monochrome. It's a real effort but my only regret is I didn't take more pictures!
The thing is at the time you think people and places will be around forever - they won't. Record them now. Some of the most fascinating shots are throwaway street corner photographs. The hair-dos, clothes, cars, shop fronts, advertisements have gone and sometimes entire areas have been flattened and rebuilt. Even the graffiti is heritage.
The lesson is take more photographs, you won't regret it.
There was this coffee shop in my town, it was in a house built in 1775 (let that sink for a moment). I've seen the house thousands of time during the past 30 years and I drank cuppas there on several occasions, it was the kind of place that one would think "It's gonna be there in a hundred years"... Last year some pyromaniac devil decided to throw an incendiary device on the house, next morning all that was left were ashes. I've never taken a picture of the place and now I can only see it in my memories.