The problem is that neonicotinoids are about as close to an ideal insecticide as we could hope to have. They're effective on a broad spectrum of insects, they don't harm plants, and they're really quite safe around mammals. For example, dinotefuran has an oral and dermal LD50 in rats of > 2000mg/kg, is not known to be carcinogenic, and is not known to be a neurotoxin. It's also essentially non-toxic to birds, fish, and aquatic invertebrates (important because of chemical run-off.) I'm not saying I'd sprinkle it on my breakfast cereal, but I wouldn't get sick from it.
They just happen to be 50 times as lethal to bees as to any other insect. So even the lowest doses used to control economically damaging pests are still going to kill huge numbers of bees, because the tainted nectar and pollen that comes back with the bees feeds the colonies.
I really like the stuff for INDOOR control of greenhouse pests. Outdoors, I won't use it.