Yes. Wireframing is prototyping. But fidelity will be low. Yes, ideally wireframes are presented with as litle visual elements as possible. So when the user is presented with the wireframe, he will only notice the function an feature. If the prototype presented to him has visual elements, user focus will most obviously be directed to those visual elements. And when we are in the process of coming up with a better information organisation and structure of the product, we cannot afford the user to focus on the visual aspects. So yes, at the wirframing stage itself you need to start taking user feedback.