My husband usually drives to work. He works less than 9 miles away and depending on the traffic, his drive can range from a short 12 to a miserable 60 minutes each way. With one of our cars in the repair shop, he needed to take BART home yesterday. Even though he needed to take a shuttle to MacArthur, he still found the BART commute pleasantly short and easy compared to the usual slow drive on 24 East.
But will he continue to take BART? Probably not. Why not? I'll have to ask him for detailed reasons but I think it's because with the extra shuttle connection, it gives you little flexibility on when you can arrive and leave. It is not fun to be chasing a shuttle, or chasing a train when your shuttle is behind schedule. Additionally, you do have more personal freedom while in your car and for some, that time is when you decompress from all the stresses of work before you arrive home.
For any of you who work close by your home, would you take BART? This is a tough one. I live in Lamorinda, so if I worked in Emeryville or Walnut Creek, I may drive more than I take BART honestly. But anywhere else, probably not.