I certainly have an in-dev roguelike I would like more feedback on. However, there are a few reasons I never participated:
1) I was under the impression that there was a strong connection between the Incubator and the bundle, such that one would be working towards having their gaming included. At least under the conditions for the first bundle, I didn't want to do that.
2) I don't always have a lot of time to work on my own RL, let alone spend a decent amount of time playing others. So I wasn't sure if I should try to get people to spend time playing mine when I might not be able to put the same effort into theirs.
3) I thought the Incubator was mostly focused on games that are nearing a truly playable state, at least with a somewhat determinate win condition, something I won't have for a while yet.