Walking from the nearest train station to work takes around 50 minutes, which is unacceptable after spending over an hour on the commute up to that point. However, biking the same distance takes 10 to 15 minutes, which is a lot better. Other, more portable, human powered vehicles do not work as well. Rollerblades do not go up hills well. Neither do these new-spangled scooters.
Rollerblades also require good flat ground and a minimum width.
On the other hand, bicycles do not need much room and function reasonable well over rough ground if it means shortening the trip somewhat. Currently, I live too far away from work to commute the entire route by bicycle. This isn't a good thing. One of the added benefits of using a bicycle to commute, is the independence from the slavery of bus and train schedules, or the traffic jams at rush hour, if you insist on using a car. On the whole, I feel bike commuting is a very liberating way of getting around.