It just didn't make the cut. For most people good health is the difference of living to 70 vs living to 75. Yes it extends life a bit, but it won't make a bad life fun to live. You can have a great life and die at 55 - or you can have a miserable life and die at 80. I'd choose the great life ending at 55 - so health just didn't quite make the top 10 cut.
I think that's shortsighted though. If I die at 60, even though my unfit grandfather made it to 83, it doesn't mean that my life of health was wasted. Health raises quality of life more markedly than any new car or boat will. The average adult is lazy, unfit, unhealthy, and they feel bad about their body. They go through decades of their life like that, and it will continually nag on them at certain points in time. A simple poll will prove the fact - at any one time I think more than half of the population claims to be trying to lose weight.
As time goes on the difference is even more marked. A 60 year old who's done a lot of excercise and avoided eating at mcdonalds twice a day compared with the average joe is going to feel much better about themselves.
And, of course, the longevity. Obesity, for instance, can shorten one's life easily by a decade. When was the last time you saw a really really fat person? Now, when was the last time you saw a really really fat senior citizen? You don't, because they're dead already.
I was forced to read a book and it said life is like 5 balls. 4 are glass and one is rubber. The 4 glass are represented by health, friends, family, principles, and the rubber one is career. If you drop the rubber one it can bounce back up, but the others will smash. Although friends do come and go career and money are comparitively miniscule in their importance compared to the other things in life.
I think you'll find further that society's particularly successful people are also often quite healthy and into fitness because they understand the importance of it.