why wear ballet shoes if you're just going out to dance?
Road bikes are great, but the ride is harsher and the positioning not as comfortable.
When the ride isn't a race and isn't about speed why not use a more appropriate tool, something more comfortable that still gets the job done?
Aside from ride quality, I don't need the extra milage and potholes beating up my custom road bike when there's no benefit to riding it. Also, while theft isn't really an issue for me, I wouldn't want to chance my custom road bike (old as it is) getting ripped off. For commuting, I think the closest I would go to a road bike is a cyclocross bike, but I'd have to have a commute longer than 5 miles each way to even consider it.