On short rides, I agree. For anything 100k and under I won't usually bother with a pump, especially if it's a road ride where I know I'm less likely to get multiple flats. Even on a ride like I did yesterday on my CX bike, rolling low pressure and hammering some rocky, rutted terrain for 35 miles, I only brought a couple tubes and CO2s.
For longer road rides, I like the security of having a pump. I've done a 200k brevet where I had 3 flats, and I would have been s.o.l. if I only carried my usual 2x-CO2 shots. On long rides through the middle of nowhere, like the 3 Volcanoes 300k which is about 100k between populated food restock points and there's no chance of buying tubes or CO2 at the checkpoints, a pump was a necessity: Gravel roads for many miles of the course. Potholed forest service roads. No phone coverage. Riding well into the dark of night, and there's no S.A.G. on a brevet.