Is a headlight required to emit light to the sides?
What the code is saying is that your headlight has to be visible on the sides. That's why most modern bicycle headlights have those little clear plastic channels on the side for the light to seep through and be seen from the side. ( The idea isn't to blind people GordonM )

Maybe it really reaches 300 feet, maybe it doesn't, the traffic police probably aren't going to pull you over and measure. But if you do get in a crash, the other person's lawyer may very well get clever and bring this up, so if you're worried about that, make sure your supplemental blinky light reaches far enough to satisfy the law.

The bottom line is that you want other bicycles and cars to be able to see you so that they don't hit you. If you are in an accident with a car or truck, there's a chance you'll be fatally injured and whether or not you adhered to the law won't mean anything. So be safe and make sure your lights are bright enough for other people to see you.