Yeah, all that stuff. Maybe even more importantly would be to survey potential commuters and people that used to commute but quit. I've heard that there exists a group of people who might commute but don't because they don't want to wear spandex. Somewhere along the line they came to the conclusion that spandex is part of the deal. Personally I suspect that this group is pretty small. Further I believe that if you convinced them that wearing spandex is completely optional, they'd find some other reason for not commuting.

Where I do think Grant and others might have a point is in regards to taking it easy vs. going hard. I think in the U.S. we want to get places as fast as possible. On a bike for a shorter trip there probably isn't that much net difference in time between riding easy and riding hard. So if the temps are cool enough, the terrain flat enough, and you can ride slow enough, changing and a shower may not be necessary at all. For me, riding at some level of intensity is half the point.