I hate the torn method also and it really gets on my last nerve. Most of the shops where this is done mark right on the line and then rip ... thus causing me to lose at least two inches that I paid for....at least in my experience.
This said, however, it does make the grain line straight. Most times I have to refold and repress the fabric, but at least it is now straight. But I always lose much more than I do when it is cut.
As some have mentioned, it is about the only way on a wide piece. But, this means I have to pay for a lot extra to get what I really need.
So, some pros and some cons! I was interested that many of you asked the shop to cut when their normal practice was to rip. I have never had nerve enough to do that! Guess I will from now on.