Car-lite bike commuter here: After five plus years of year round commuting, I have averaged 1.5 crashes a year, while the average damage per year is less than 20 dollars, the total maintence due to things rusting up is also about 20 dollars a year. I'm sure that a couple of my accidents would have pwned a fancier bike than my steel beast of an old Mountain bike.

I'm not saying a more responsible, attentive, and skilled rider than I wouldn't be able to ride an expensive bike year round without problems. I'm certain it is just an expensive waste for myself.

On the other hand once a week I'm late (what can I say I'm a dumba&&) and having a lighter faster option might be nice. Of course these are also the days when I'm likely to have a crash, and invariably carrying the most work related extra stuff.