Let me chime in here and say that Nutaku is not wedded to the freemium model, as our recent sponsorship of Everlasting Summer should demonstrate. Right now we bring over DMM games which are built on that format, but we have every intention of expanding our selection in the future to include non-freemium.
I've made posts on a few forums talking about how our ultimate objective is to foster a native-English adult game development scene. There's a huge demand for sex games of all sorts, but few methods to distribute them due to restrictions on major platforms like Steam. Nutaku wants to change that.
@Alucard - in our experience sex is supplemental to gameplay. As you said yourself, people can get free porn anywhere, but good games that seamlessly integrate adult content are almost impossible to find. Rather than move in the Luv Bingo / Luv Slots direction, we'd like to see more games like Aigis or... for example... Breeding Season.
@kisu - Everyone loves Kancolle We'll be expanding into mainstream games in the near future, so who knows...