Mark, I can confirm that it wasn't a cost issue. As you quite correctly surmised, neither company needs to be as sensitive to the cost of the components as their customers will pay for superior performance. If I remember correctly, Ripple had performance concerns with them particularly with clearance of the line from the blank in the guides near the tip (they were noisy and were slapping against the blank) and they were also concerned about the strength of the guides.
I know Carpenter tested them and decided against them in their GT rods. i think Konishi San did not see any performance advantages in them and had concerns about the overall strength of the guides as well.
That said, I found them to be strong enough (to date). The first trip i took the rod with the K guides on was actually with Tak and Konishi San . As it was driving me crazy rattling through the end guides, the look on Konishi San's face was one of familarity!
I do note that the company that has always had the option for the fanciest guides, Fisherman, has also eschewed them to date.
Brice, you really think premium manufacturers like Carpenter and Ripple Fisher would care about a little bit of extra cost for a K guide? No way.
Even if it did add cost, that would go onto the retail price of the rod. At that level of the market consumers are not especially sensitive to small moves in price.
