Those who make lots of kilts rip the wool tartan for two good reasons: 1) it gets the job done quickly, without having to pull a couple more threads and pick up lots of little thread bits, and 2) it produces the straight line with built-in ravel-resistance mentioned earlier. I've cut both 13 oz and 16 oz, and ripped both weights of wool also. Ripping is generally preferable; cutting is perfectly acceptable.

Fabrics other than wool are cut. Most do not rip easily. Even cotton broadcloth, which does rip, leaves a curled edge which needs to be ironed flat again.