When I grew up, a "10 speed" road bike was what most adults and teenagers rode. I routinely took road bikes on roads like the above (minus the mountain). In fact I lived on a dirt road. The original tires on my 80's roadie were 28s, not the 23s that often comes on new ones.

It was the mid-90's before I got a mountain bike and I got it specifically for trails that were too difficult to pass on my road bike, - sand and sometimes deep mud. It wasn't because I was worried about breaking the road bike.

Reality is though that there's probably only a been a handful of times in the last decade that I've ridden in places that demanded a mountain bike, - like going down an actual alpine trail. It's fun but I don't do it all that often anymore. I've commuted on my MTB and did so exclusively for a few years. I also felt that it was better to have something more durable, - just in case.

Last spring, after 3 years of riding in the winter, road salt had taken it's toll on my MTB's drive train. Plus I had agreed to do a triathlon with my wife so I started riding the road bike again while I fixed up the MTB and for training. I'd hardly ridden it in 10 years. It felt strange at first but I quickly got spoiled with how much quicker (and fun) my commute was on even an old, relatively heavy road bike. We also got my wife an old road bike for her training. It reinvigorated her interest in cycling. For the last 15 years she'd ridden nothing but MTBs.

Now it's winter and I'm back on the MTB. My commute takes a lot longer. It's a different style of riding and I agree there's a sort of bomb-proof appeal that the MTB has. In the winter I enjoy riding on hard-packed snow more than bare pavement. Overall though, a road bike will be my commuting bike for choice for 8 or 9 months of the year.