I don't know why you are apparently angry at me
I know of a cosplayer who cosplays The Evil Queen from Snow White in a cosplay she bought. It is amazing. I've even seen people slightly modify cosplays they bought at Disneyland or a Halloween store, and it looking really really good. I know people who bought packaged Bleach cosplays which are slightly inaccurate, but not so dramatically that I would say "That's not cosplay."
Maybe that's not what you are talking about, though. If it isn't, could you clarify what you mean?
I doubt Facebook created the event. It's probably not an official Facebook event. Anyone who belongs to Facebook can create events and even create ads for them that look official if they are willing to pay the money. Hell, I myself created "Change Your Status to a James Joyce Quote" day and if I was willing to pay the price I could have had little ads targeted to people who have certain interests show up on the side of Facebook.
The point of this event seems to be to go out on a day that isn't a con or Halloween. Maybe you will be all alone or maybe you will be with your friends. Maybe you will go to school and someone you didn't know was into anime or cosplay shows up in cosplay. Either way it's something different and breaks up the monotony of the average day.
I would say that another point would be to encourage cosplay in every day life, which I am all for. Life is too short to wear boring clothes. However I am too shy and scared to do it by myself. So if there's even a chance that other people have organized to also do it it makes it much easier for me.
"Tell him 'Fine, there's no way I'm dying before you do,
you morally bankrupt colonel with a god-complex.'" - Edward Elric
Going to ALA, Gallifrey One, and SPN Vegas Con