Why it matters
Structure feedback is cheap at the sketch stage and expensive after visual design, when stakeholders react to colours instead of content order. Wireframes force the important argument first: what does this page say, in what sequence, to make its case?
How it works
Grey boxes stand in for images, bars for text, real labels for sections: enough to walk a user journey and test the message hierarchy, little enough that nobody comments on fonts. Approved wireframes then brief the visual design cleanly.
What to do about it
When reviewing wireframes, resist "make it prettier": that's the next stage. Ask instead: is anything missing, is anything unnecessary, and would a stranger follow this order?
