I know it's not fun to be stuck at night fixing a flat in the dark, I did it a few times. I, like all of us, do all I can to avoid flats and since my badluck streak last spring I've been almost 10000 kms without a flat but I still keep my flat repair kit in a small saddle bag. My kit contains tools, 2 tubes, a small frontal light and a patch kit. It weight about 1 1/2 pound (guessing here) and I don't go without it
I firmly believe that fixing flats on the side of the road is something every cyclist should be able to do.
Last summer I repaired flats for desperates cyclists twice but if everyone could fix their own flat I wouldn't be able to make new friend as easily.
But that's just me