1. One-way trip by car, express bus or train is about 12 miles. By bike it's 24 each way. I work long hours. 48 miles r/t is a burden on a work day.
2. Route has a few huge hills that can be fun to tackle on the weekend but are a bit much before andy after a workday.
3. Much of the trip is just plain unpleasant because of high speed traffic and gridlocked congestion on roads with inadequate or no shoulders. I'm an experienced city rider; this stuff is BAD.
4. I often work until well into the evening. After dark, #3 feels like I'm really taking my life in my hands.
5. Only way to have adequate bike security is by paying the $10 motorcycle charge to park in a garage three blocks away. That's more than bus fare. I used to have a cheaper and closer deal but they kicked as part of their post-9/11 security measures. I do have a folder that I could bring inside, but it's not enough bike for this kind of a trip.
6. I have to wear suits. Yes, there are plenty of workarounds like leaving it in the office, but that's just one more thing on top of the others.
I LOVED commuting when I had a mostly pleasant 13 mile trip each way and am really sorry it's become impractical where I now live. Still, I'll do it once in a great while if it's the only way I can fit in a ride that week.