The problem I have with ripping cross-grain is that it damages the fabric up to 2" in from the rip. You can't see the damage with the naked eye, but it is obvious under a microscope. Even if I were to refold the fabric on-grain, I would have to trim 2" off each ripped edge to be sure not to have weakened fabric in some of my blocks, since I don't have a microscope handy to see if the fabric was damaged only 1" from the rip.
At least they were generous with the cuts to make up for the extra I had to cut off from each end.
I don't have a problem with ripping fabric along the lengthwise grain, especially when long borders are needed, because it is a cleaner rip with damage not extending as far into the fabric. Cross-grain ripping, on the other hand, is the pits.