I'd just like to point out that I ordered the boxed adult version from J-List and I never got a Steam code (I did get a download code to download from JAST). This doesn't particularly bother me, but Mangagamer DOES offer free Steam codes for those who purchase from their site. I was reading some comments on Littlewitch Romanesque's Steam page and it seems that for many Steam users, being able to play the game on Steam is very important to them. Since JAST is selling the adult version at a premium ($40 vs. $25), I think it's a nice show of goodwill to fans to let customers of the premium version have a Steam code as well, especially when the alternative is buying the discounted game at $25 (or even less when there's a sale) and applying an unofficial decensor patch.
I'm actually sort of surprised that JAST is giving the official nod to use this patch. The Starless matter is one thing, but in this case the Steam version is directly undercutting the adult version by reinstating "premium" content. In this case the Steam version came several months after the official release, but what if there was a simultaneous release of the adult and Steam versions? Steam could end up cannibalizing all of JAST's digital sales of the adult version, assuming a decensor patch was available in quick order. Besides the issue of lost revenue, it would create a false impression that there's no demand for the adult version, when in fact demand for the adult and Steam versions is being mixed together in the Steam sales numbers.