Because they are hippies who fear an alternative energy that might actually work, and they listen to horror stories about things like Chernobyl and Three-Mile Island, ignoring that fact that neither of those are possible with a well-designed, safely implemented reactor. Things like a nuclear plant going critical is only possible if the plant was designed by a drunken idiot, and staffed by retarded turtles; neither of those is the case with the reactors in Japan, which are fine.
Thing is, about 70% of the world's population is comprised of idiots. Nuclear power isn't anywhere near as safe as we claim it is. All it takes is one error, one fuckup, one miscalculation, and you've got a plethora of mutated babies.
Look at Japan. It's one of the most technologically advanced countries on the planet, and yet nobody realized the dangers of setting up nuclear power in an area prone to natural disasters.
Remember, people used to say smoking was good for you.
On another note, last time I checked uranium isn't exactly a renewable resource...