Why should I have to pay $15 a month to have to generate my own content or rely on fellow gamers to generate it? That's the devs' job. If they make the game F2P, then we can talk.
I think you miss the point--it's about the fun of creation and adding to the game. Plus, it gives the advantage of having others who do like to do this stuff give those of us who don't something more to do!
Even if XP/Merit/etc isn't given from these, I'm sure people would still explore them for grins.