Ask HN: Requirements-Based Project Management

My company has used quite a few project management tools over the years, but none of them have fully satisfied us. Currently we're on JIRA which is great for tracking at the task and issue level, but we feel that it doesn't have great support for managing documentation and application requirements.

Our vision for a PM tool is based around writing requirements and documentation first, then generating tasks based on creation of or editing those requirements. A requirements list might look like:

    Business
    |-Orders allowed only from 8AM-5PM
    |-Order minimum is $5
    |-...
    UI
    |-All tables have an 'Export' button
    Etc

Each requirement is a first-class item that can be modified, can have comments attached, etc. When changing a requirement, you can generate a task that is inserted into a backlog or sprint for a developer to work on. The requirements document would be version controlled along with the tasks that are generated for each requirement or change, so you can view requirements of a previous release. You would also be able to diff the requirements between versions to see changes between each and the tasks completed for those changes. Bugs could be filed against a requirement that is not working as intended.

The benefit we see is that your documentation is directly tied to your project management. Before a work task is generated, a requirement must be written in the documentation so it forces the documentation to be written (which is usually so rarely/poorly done). A lot of PM tools can integrate with Wikis, but it always feels like an after-thought and the wiki inevitably rots in many projects as effort isn't put forth to maintain it.

So, do any tools exist that do what we're searching for? We're not opposed to writing one ourselves, but obviously we'd like to save time and money by adopting an existing tool. Would anyone else be interested in using a tool like this? What issues or problems do you see with it?