My guess is that the plants are under more stress than ones grown conventionally, so they produce more anti-pest compounds that we interpret as flavor. (Who decided to eat veggies anyway?!) The theory holds for leaves and stems, anyway. Maybe it works on fruit too.

I've only recently come around to eating cucumber. I wouldn't touch it for years. I wish we could easily get organic produce around here. If I want more than my local supermarkets' limited selection, I have to make a 20-mile round-trip.