Depending on your age and physical condition, you would have died.
I've seen guys without helmets plow into the back of a car at a (relatively) low rate of speed. You may not get a severe head injury, but its good for a broken jaw and worse. So not only do you need a hemet, but one that protects the entire head (is that what you call full face?).
Not wearing a helmet, even on a bicycle, is stupid.
Yeah, I had on a DOT/Snell full face helmet. I would never wear anything less on a motorcycle.
I crashed my mountain bike once and flipped over the handle bars. I was wearing a helmet and my head HIT A ROCK on the trail and broke the helmet.
It wasn't until I took off my helmet, that I realized I'd hit my head, I had no injuries to my head! Not even a headache.
Of course I did break my collarbone...
Helmets work
The full face helmets can be good for protecting your jaw, teeth, and pretty face, but they can also result in a snapped neck if they catch the wrong way. They also cut way down on your peripheral vision which is your first line of defense when street riding.
It's all a trade off. Bike riding is an inherently hazardous pastime as are numerous other activities. As someone old enough to be Big Ben's father, I am no longer inclined to get on a bike with or without a helmet, but when I was his age, I rode without a helmet and never thought twice about it. It was "great fun" back when I was invincible.