It has been shown that when towers collapse there is a twisting action involved. To eliminate excess twisting movement in a tower, the base can be made to turn or mechanical advantage can be applied via the guy wires.
It is not a good idea to directly connect a guy wire to a tower leg if for no other reason than the abrasion between the guy and the tower leg will probably erode the galvanizing provided on the tower and start rust areas.
Lately there has been discussion that the use of torque arm guy brackets is of little value. However, I believe there is considerable value in using them. First, the structure of the guy bracket distributes the load evenly to all three legs. Second, the bracket provides a properly designed guy attachment point. And last, the bracket does provide some mechanical advantage. Using Rohn 25 the approximate radius of the tower is 7.4 inches. A 12 inch torque arm at 45 degrees increases the radius by 8.6 inches, providing better than twice the mechanical advantage.
Pictured below is a guy bracket I built prior to the assembly being galvanized. I mount the bracket at a point two tower sections join so that the inside bolts rest on a double nut tower bolt and where the tower legs are double thickness and 90 degrees opposed to the tower through bolts . In later versions I used only a single bolt outside the tower legs. Similar devices are available from the tower manufacturer.
A simple point of attachment can be made with a piece of flat stock with holes drilled to match the tower bolts. The eye of the guy goes inside the bracket and is retained with a 7/16 inch bolt with a nut, lock washer, nut combination so there isn't a lot of compression on the bracket. These have been retired from use in favor of torque brackets. Of course, they would be a lot better looking had they been galvanized. If rotational forces are not an issue this type may be acceptable.