<i>The second area is that you aren't getting the right feedback from customers.</i><p>Yes, if you are bringing your customers into the office and actually watching them use your product.<p>Usability testing is and always has been one of the most lacking areas of web development (probably other types of consumer software as well, but web is my area of expertise).  A good tester can address these issues up front more than anyone else in the organization.  Everyone else is too close to project to give it a fresh look.  It's no substitute for real usability testing, but it's a good deal closer than anything else internal.