To a certain extent, wireframing will always be a collaborative effort between the UX team and the rest of the business as a whole. In that sense, no single person is responsible for producing good wireframes. A good UX professional will pull the necessary stakeholders into the wireframing process to ensure that all business requirements are being met. This is where a collaborative and iterative process really helps out. By running new ideas by stakeholders at different points in the design process you'll find that you're able to gauge quality and problem-solve much more easily than you might expect with more of a "waterfall" approach.
As far as who's responsible for actually producing the wireframe documentation, @dopamino has nailed the real-world challenges with answering this question. I'd add only that, in an ideal world, the UX team is producing wireframe documentation for the development team that has been well-vetted and reviewed by stakeholders (both internal and external). In the end, the designers (both UI and UX) should have final responsibility of creating and understanding the in-depth issues surrounding any design, and should be able to present the design and speak knowledgeably on the subject.