The whole road rash thing can be almost as bad as having your head busted open. I don't know if anyone here has ever been burned badly, but road rash is virtually the same thing, only they have to pick gravel and chit out of the meat before they scrub it down and bandage it up. My neck was serverly burned in a soldering accident on a commercial refrigeration unit, and let me tell you, the pain is something you don't want to experience, nor the visits to the doctor to have the wounds debreeded (I think that's the term), where they remove the bandage and then scrub the wound with a sponge and phisohex. That's to let it heal from the inside out, rather than scabbing over and causing big scars. It works, but laying on a table having that done is not something I ever want to go through again. So, I wear full gear, 98% of the time...only when it's 98 degrees and 90% humidity might I take the jacket off when around town. The new mesh jackets with armour are really not too bad as long as you're moving a little.
Three things are likely to get injured in a bike wreck: Head, feet, and hands. I have seen 4 or 5 bike wrecks in my lifetime, and in at least three of them the person was wearing tennis shoes, which came off immediately after they hit the pavement. Their feet were not pretty to look at. And that was just the skin/meat ground off them, much less the broken bones. And there are a lot of small bones in your feet to get broken, and they take a while to heal. Good boots and wicking socks are a good idea...
In the early 70's I didn't worry about that kind of stuff when riding a death trap chopper. Nowadays I'd just as soon be around as long as possible.