Sometimes ideas are small and specific, sometimes they are big (ex. add a button vs. create an app that does x). Currently an idea is assumed to only be for a feature.
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It is now possible to promote Ideas to Initiatives.
You can read more about it here: http://blog.aha.io/promote-big-idea-to-roadmap/
At this time, we do not have plans to promote Ideas to product. However, it is possible to create a custom field on your Idea to link to a product.