Wireframes convey that “this is all up for discussion” : The rough feel encourages discussion. We call it a look no one is afraid to criticize. Wireframes are really quick to make, so don't be shy with giving feedback! Each screen probably only took a few minutes to make; don't worry, their author won't mind doing them over from scratch. What matters the most at this point is the final ease of use, so going through a few iterations is normal and expected.