I think Ruger wants to discontinue the standard LC9, this is a way of easing the transition. I believe the LC9 was rushed to market because Ruger didn't want to miss out on the mini 9 fad, Ruger came up with a design similar to other wildly popular guns and launched it, same with the LCP. In the mean time they worked on the LC9S which is more like what they intended. The S version has one of the sweetest triggers I've encountered on an autoloader, really that is the design they should've used on the SR series.
Most people I know who bought the LC9 say they like the manual safety but not the long DAO pull. This would be a good way for them to upgrade.