[quote=@Jig]
As I see it, the interest check is a place to pitch a prototype of your OoC, and see if people might be interested to save the pain of all of the world-building and planning that can go into an OoC, only to find that nobody actually wants it.
[/quote]

To add too this, it can actually help with the world building.

With an interest check, it is a good idea to pitch a very basic idea and try to drum up interest by allowing others to participate in that idea's germination. People feel more inclined to dedicate time to something they helped to build.