Actually they did. In the early 90s the Team Miyata did come with it, but also Koga specced it on its FullPro. The Pro got the Hardtlite (steel) fork in 1991, while the FullPro came with the bonded al fork. As a kind of upgrade. Apparently a popular feature, as in later years the al fork was also chosen for the FP.

Koga also had a fork similar in contruction to the bonded al ones, but with carbon blades. I doubt whether there ever was a US Miyata issued with that fork.