Being a lifelong runner, I agree with you 100%. I'm not panicked or unreasonable about it or anything, but I do protect my body. (So glad they canceled Boston by the way.)
I would encourage people under 60 to consider the very real possibility that certain physical activities that you enjoy may become difficult for you. Some may even become life threatening. Who knows? Hiking or running at certain altitudes, etc. Consider the sense of loss you might feel at not being able to do workouts that seemed a breeze just last year? Or how would you feel if you suddenly found that you need frequent rests to "salsa the night away"?
This virus is likely harmless if you're 15 or under. It's fairly deadly if you're over 60. But if you're 15 to 55, there's a whole lot we don't know right now.