Right - the additional cash from an IPO would just let them scale faster. Maybe it takes 2 years on average for a piece of content to pay for itself. After those two years, everything they make from it is gravy. If that's the case - it seems reasonable want to do this IPO.
On a whole, their content is just average - but, I really do like the way they've setup Demand Studios. Of course, as someone who has some content websites, they just represent more competition, but I do admire them for taking this concept and running with it.