We were taught that too ... and I have never used it in quilting :)
I had one fabulous week of a class with John Willard - "spontaneous geometrics" - and he showed us how he will often cut which ever way the geometric design he is going for, is laid out on the fabric. Sometimes straight width of fabric, sometimes on the diagonal bias, sometimes just off straight.
Most of my creations are from width of fabric cuts, so I do work on getting a good straight edge without 'v'. But I'm prepared to cut at whatever angle I need, to get the right effect :)