One value is that the complete (corrosive) surplus round costs less than a jacketed bullet -- comparable to a commercially cast boolit, in fact, if you buy enough of 'em at once. This method also doesn't require buying brass, powder, and primers, just powder.
That said, there may be issues with pulling bullets from surplus ammo; most if not all are sealed into the case neck in some manner, and the ones I've looked at closely (Bulgarian 1972 and Russian 1973, both silver tip 147 grain steel core/jacket) have a pretty heavy crimp, making it difficult to pull the bullets without marring them (may or may not matter for a plinking round). As noted, they're still corrosive primed, so you have to clean thoroughly after every shooting session, even a single round. Still, if you're after recoil reduction, there are some good things along this path; one to try is reloading the cases with the original powder, but use half to 2/3 as much with a little wad of polyfill (half a grain, maybe?) to hold the powder at the head end of the case to ensure good ignition (won't even use up your Trailboss, and you get a little Russian etc. military powder for other uses, if you can find data for it -- though you get two or three times as much with the Trailboss refill).