santrix, you are spot on. I'll still blather on though!
I want one of these hi viz goretex jackets for several reasons.
1) To lessen the degree that my goretex jacket soaks up water and is cold and damp the next day.
2) Riding down the Motorway in the dark, i've seen so many bikes go past me with riders wearing all black, once they've pulled back into an inside lane, they are nearly invisible from behind. I'd hate to be in a similar position, knowing that a car may be overtaking, then decide to pull into a poorly perceived "gap" at the last moment to exit the slip road, taking me out in the process.
3) though's crossed my mind that if I do get knocked off, at least I'll be visible while lying on the road!
4) Having seen other people wearing them, they make themselves far more visible to me, so it does work for some of us.
Even though I ride my GS with the lights on, (not optional), I also ride with the foglights on. The different reaction from the traffic between riding the GS and my Yamaha is obvious. The assymetrical light pattern catches quite a few car drivers attention, and they move over to let me pass. Having added LED fogs to the Yam, this has improved drivers awareness of my presenceas well.
I still treat every other road user as a dickhead though, I unfortunately include other motorcyclists within this group.