Well, I use Aurifil 50 wt. almost exclusively for my quilting because it is an amazing thread -runs smooth as glass through my machine and never breaks or tangles. My curiosity up, I put in a search for Aurifil 80 wt. and not only did I find it, it is available in my absolutely favorite online place to shop for quilting material -especially precuts. It is available at Fat Quarter Shop, and this weight is specifically for APPLIQUE quilting, both hand and machine. The Shop seems to have several color-coordinated sets and even has an Aurifil Applique Thread Monthly Club, so it must be popular among those who applique thread.
Given the high esteem in which Aurifil thread is held, I suspect you just got a bad spool.
Good luck!