I don't know, I think they are always changing things...
But sales go down probably because if you don't constantly add content you get buried by the competition..I haven't added anything and it has been going down...
and also they are bringing so many new products, like cheese boards, ruler, tie bar, cookies and soooo many things...that is more products that people add with the quick create....So the marketplace is probably getting much bigger also because of that.