Hype is awesome for creating interactive prototypes but I miss two things:
A symbol library that would be available across documents including categorisation function. And maybe the ability to create packs of symbols. Such as iOS8, Material design etc.
A place where you could download / purchase or freely share symbols. Ideal you could search for symbols according to categories, and preview them within hype itself, and add them to your document.
This could create great ecosystem of symbols that could get interactive prototypes of the ground very quickly and make hype the premier interactive prototype tool.