The loaded chamber indicator doesn't have to be there, the 4.25" barreled 2.0 guns don't have it. I'm guessing it's on the 5" guns because it was some requirement for the Military Handgun contract S&W submitted the 5" guns for.

They probably haven't made a 2.0 CORE for the same reasons they haven't made a 2.0 compact or the 5" guns without a thumb safety. They just haven't gotten around to it, or they want the fanbois to buy a gun they don't really want (a standard 4.25") then buy another one when they finally make the one they really want (a 5" with no safety, a compact, a core, etc). Worked on me.