the Lazy Randonneur wrote an excellent article today (that was reposted by the People For Bikes Facebook page) about the author's refusal to "dress like a traffic cone" while he rides. And it's an article that I totally agree with, but I will admit that I do dress like a traffic cone.
The standpoint is that the author, who we'll call LR for the purposes of the article, does not wear reflective clothing for his riding. The standpoint is one that I've ranted about many times: that cycling is just transportation, and he wants to get where he's going with the absolute minimum of fuss. And that's a standpoint that I agree with, wholeheartedly. I make recommendations on bikes and equipment that will make your bike transportation easier and more convenient, in my opinion. We're not going to get more people to ride unless we do that very thing - make it easy as (or easier than) driving a car.
That being said, I wear a fluorescent green jacket when I ride my commute each day. Would wearing a dark jacket, which is what I do wear when I ride the bus or for most of my local rides when I'm not commuting, be sufficient? Yes. I am of the strong opinion that most problems cyclists encounter with traffic are alleviated when they ride properly - out in the middle of the lane, away from the curb, and controlling the traffic around them by taking up the space that they're legally allowed (at least in Ohio). And if you're riding at night, using proper bike lighting on the front and back of your bike helps with nighttime visibility issues.
So why do I wear a fluorescent jacket when I'm riding, if I agree entirely with LR?
Because it's worked for me so far. I've been riding regularly for around five years now, and I have yet to be involved in any sort of accident. I rarely even have close calls (granted, after five years, my definition of a close call and a new rider's definition might be two different things) because I ride conspicuously and look conspicuous.
Other than that, I try to do as little as possible to change clothes from my riding clothes to my work clothes. And I ride in such a way (slow!) that makes that easier since I'm not sweating as much.
But if it ain't broke, don't fix it. I have a lot riding on my regular daily safety. And if I'm going to ride every day I should do what I can to remove as much of the risk as possible. And though my riding style ensures that drivers are going to see me, wearing a fluorescent jacket or vest makes that even more clear. That's not to say that people who don't partake in traffic cone chic are risking too much. It's just my preference to do what's worked for me.
People, not speed.