I am sure the major RV manufacturer would love to build and charge for high-end quality. If people were willing to pay for it they would be buying those top drawer units and the average TT would be setting on the lot.
I believe the comment that the quality is inconsistent is perhaps the most accurate description. That, plus the fact that some peoples “major defect” is not an issue to others; make a defect hard to define.
For example, I consider a TT where the retracted slide blocks the bathroom door a major design error, other could care less.