You could just easily get hurt doing safe things. Your taking your shower, slip, and bam you're a goner. It's just bad luck.
People tend to be paranoiac, though. A few years back from now, people didn't even think of wearing helms at all, be it in biking or other sports, you just didn't saw people with them. Then there was the huge publicity over it, resulting in people suddenly becoming paranoiac about it. There's only a few times in your life the helm is truly going to be useful. The bottom line is, it's good to have, but overrated.
Use your judgement. If you don't wear one, be more careful. And if you know you're going to try out something that is potentially more dangerous, like the park, wear one for sure.
As for the 'cool' factor, I think it's irrelevant. The last time I heard that nonsense was when I was 8 years old, and at school everyone thought helms were uncool. But ever since, that perception has changed, and I haven't heard of it since.