I rip all my fabric so that I get a straight grain. I don't think it harms the fabric at all. A bit of steam ironing puts the frazzled edges back in shape, and that 1/16th or so of fabric is part of the seam anyway.
I find cut fabric is often off the grain and uneven. I wish my LQS would rip, but I understand the clean cut looks nicer, but it is not the best way to make sure the fabric is on grain.
When I rip, sometimes I can get up to a 3" difference from one edge to the other...that is a huge waste from cutting.
Diane