People, including the foundation, like to get public sentiment about ideas and have no effective way of doing that besides submitting a preproposal poll, which often results in comments from pedantic people, like myself, saying "this shouldn't be governance" or people just voting "invalid question" and not offering an opinion on the question.
Examples include the resent poll about improvements to the Camera, Canessa's poll about adding a second sun, or Jenn's poll about adding a search bar to the emote page in the backpack.
Most people don't even know canny exists, and of those that do, most don't participate.
it would make sense to make it as easy as possible to get a sample of community sentiment without having to create "invalid" governance polls.