I had to work with express, and one thing that I missed was having a Response object where you build your response and then pass back to the framework at the end of the request. So I built my own proof-of-concept-framework to understand why others don't do it (maybe it was just not possible).
Many people will tell you that there are a thousand frameworks out there, go contribute to one of those instead of creating more noise. For me doing a framework was a great way of learning the internals of node, the kind of things that frameworks are designed to hide away from you. Go for it, start your own open source framework and put your ideas into practice. The ecosystem is still maturing.