Agreed. We have actually implemented something similar to what you're looking for but something like a backlog at the Project, Program, and Portfolio level would really helpful. Ideally a Portfolio backlog that would be filtered down for Programs and Projects. Especially for requests, this would be nice.
We created a template (with no tasks on it- so its just a shell of a template) that has all the needed RQs attached to it. Our PMs are instructed to attach this template to every project they open, and then they can create issues/requests for whatever they need (eg, Studio Spec Sheet, Art BUying, etc) and its tied to their project.