It has been recommended by other sailors that wire cutters be included in the kit of tools that you carry on your boat -- and also that every chase boat at a regatta should be equipped with a pair of wire cutters. The purpose is not to disconnect the mast from the boat, but to cut rigging if necessary to rescue somebody.
If you are responding to my post, as quoted here, I was responding about using wire cutters vis-a-vis beach cats. You're correct about the reason for cutting broken masts free on big boats, either to prevent damage to the hull or so that a shorter mast can be jury-rigged to complete a journey.
Wire cutters are sometimes used to cut the rigging and let the mast go in the case of beach cats, too, when it is necessary in order to salvage the boat. But the primary reason for having a set handy on a beach cat is to free someone who may be trapped by rigging that cannot be cut by a knife.
