Well, I have the opposite opinion. I specifically bought the Shield as a CCW pistol, and as such, I have no use for a rail on it. In fact (call me a curmudgeon, my family does) I don't like rails on pistols in general. I wish all pistols came with the option of having a rail, or no rail...I like the clean, classic lines of a smooth dust cover...although, I guess "classic" is a bit of an oxymoron when talking about polymer pistols.
Anyway, back to the Shield...since I bought it for CCW carry, it won't have a light attached...so, no need for a rail.