Let me remind you of a similar situation - 50 years ago, it wasn't common knowledge that smoking was harmful. Many people smoked. Then, overwhelming evidence showed that it was harmful. Then, there were widespread campaigns telling people just that. Today, not as many people smoke, and not to the same degree. Success! Should we have given up on teaching people sense?
Second, what makes you think - assuming that cell phone emissions are indeed significant enough to be harmful - we can't have tech that works as it does now, but is less harmful?