I'm sorry, I disagree with a few aspects. First, I've never had issues maintaining good grip on the bars while pulling the brake levers, whether from the hoods or the drops. If anything, in an emergency stop, I've gripped the bars too well, causing my arms and shoulders to tense up rather than remaining loose.

Second, your hands on the bars are only part of the steering input; you steer your bike at least as much with your butt through the saddle as with your hands on the bars.

Third, your feet may well be needed in an emergency situation; sometimes the best maneuver isn't to stop but to accellerate or to bunny-hop.

Finally, even if I had a coaster brake, I'd put a front caliper on too. But then I'm one of those belt and suspenders guys who puts front and rear brakes on my FG bike (essentially giving me 3 brakes).

So, no, I don't think hand brakes are dangerous in traffic.