Why do we call it "raising awareness" in reference to certain things?

I always see people with ribbons or bumper stickers or even more quirkier methods (like posting your bra color as your facebook status, for example) that claim to be raising awareness for issues like breast cancer or autism. I simply find it hard to believe that there are many people that aren’t “aware” that breast cancer is out there and could potentially affect anyone on a personal level. On the contrary, there certainly are afflictions that may be more rare, like ALS for example, where the general population may need to be educated.So why do we say we are raising awareness in instances where most people are likely already clued in? Wouldn’t it be more accurate to just call it supporting a cause? Of course I’ve seen it put both ways… I just wonder why we use “raising awareness” at all in these cases. Can anyone enlighten me?