While these days there is a lot more information on Russian designations for most of their weapon systems, many of them can still be pretty confusing for things like SAMs. There are often so many varieties where it must be quite difficult for any pilot to memorize what he's up against, especially with the Russian designations. I'm sure the reporting names, especially for things like radars, are useful too. Big slab looking radar on a big 8x8 truck? Probably a GRAVE STONE or TOMB STONE and it kind of looks like one. Easier to remember than whatever the exact designation.