That's exactly what happened with the Shadow Ninja Color Change figures. The Shadow version is just a straight repaint of the original figures from the Nick TMNT line, so it seemed like a no-brainer that all four would see release, but apparently it wasn't in the cards for Raph and Don to become Shadow Ninjas like their brothers.
These two are seriously some of our favorites to have out and just mess with while watching TV or looking at our phones while listening to TV. The gimmick is neat too, but we don't play in water too much while sitting on the couch, so the black shadows are always present.
We should mention that Leo actually has TWO Shadow Ninja figures, the first was released as a SDCC exclusive that did not have color-change action or any articulation. Which is pretty annoying that a better version came out at mass-retail for less than $10 when some people probably paid quite a bit for a figure that became somewhat obsolete soon thereafter.