If there was ever a snub that is up to the .357 Mag, the SP-101 is it. Not only is it built like a tank, the gun has superb recoil management characteristics- even with the factory stocks. They are accurate too, and the 3" .357 we had around here for awhile shot as fully well most 4" fixed-sight .357's I have handled. I had bought that gun for my wife, before she discovered that the Springfield XD fit her better than anything she had tried.
The 2" SP pictured below was brought to me by a detective buddy who wanted the windage regulated a tad; this "before" group was fired at 25 yards offhand, with 125 grain magnums. We moved the group right onto the orange dot before we were done.
But back to your original question- why build such a tank in .38 Special? I think it comes down to sales. There are agencies like NYPD, plus innumerable private security outfits, that specified ".38 only" for decades, and Ruger understands that there is always going to be a market for a good .38 snub.
If you like the SP mag, go for it. I'm betting you'll be able to handle it just fine, and it'll always chamber the .38's if you're so inclined.