Why?

Well, in my experience people who claim to think or work “outside the box” do so because they either do not know enough to work within the box is or don’t understand how the bits in the box are supposed to fit together.

It’s become a euphemism for:

I don’t really know what I’m doing
or
I can’t articulate what sets me apart from the competition

I’m sorry if you were the first one to coin the phrase, but the wrong people got hold of it and redefined its meaning.

thomas valaitis marketing outside the box