Haven't been to Knott's in a few years so some of this may be outdated but here is my thought.
Knotts has had the Old West theme for YEARS... they know what they are doing. They have a Stagecoach, Ghost town FULL of eclectic shops and various crafts (XMAS Craft Fair), Old style photographer, Blacksmith, Actual theater that isn't in a saloon, panning for gold, and a really cool leaking water tower that rocks when it's hot outside! Everything from the candle shop to the knife shop screams OLD WEST... I have to say while I am not a huge fan of Knott's overall, they did nail that theme down.
Frontierland has- a bunch of Disney stores that look like the Old West as you run past them on the way to Thunder or someplace else. IF the line is too long you might actually stop and play at the shooting arcade which is the only other official "attraction" in Frontierland (Twain is part of NOS officialy).
Anyone else feel a little cheated here?