I work at an office where "business casual" is the norm. I commute all year in office clothes, and frequently ride to outside meetings or go to cultural events in the same or nicer clothes (they don't call them "sports coats" for nothing).
My commuter bike has a Wald clamp-on chainguard, which would not work on derailleur bikes, but works great on SS or internal-geared bikes. I still use an ankle strap on the right (I really like the JANDD -- the clipp takes the stress off of the velcro, so they last much longer while holding on as well as anything else I have used).
When it is below about 30F, I wear wool long underwear under my corduroys. I wear a cardigan sweater under my chartreuse bike jacket. The jacket comes off when I want to look like a normal person.
In the summer, I wear cotton shirts, frequently polo shirts, and I wear the button-up shirts without a t shirt. I slow down, but sometimes I get a little sweaty. Big deal. My deodorant does not disappear from light use.
I still drive when it is impractical to ride, but this is a good discussion for those who are trying to expand what is practical.