Think of requirements as inventory or as component materials in a storage bin with a shelf life and a carrying cost. Inventory isn’t free. You have to pay someone to produce (model and document) requirements. You need a supply of good, current (fresh) requirements to produce a quality product.
There is no perfect, fits-all template or set of documents which will be effective across all companies or even for all of a given company’s projects. The business analyst should work with internal and external stakeholders to determine which communicative tools will best serve for each project effort and model requirements accordingly.