Tmax,
If I recall rightly, Honda came out with the CL72(the 250cc Scrambler) in 1965. Then increased the displacement to 305cc(the CL77) in 1966.
But the Brits had large displacement(well, considered large in those days)500cc-650cc high-piped "dual-purpose" factory bikes since at least the mid-1950s or maybe even way before that time. I'm sure someone, especially Greybeard, could correct me on this if I'm too conservative on my dates here.
So I'd have to say that, yes, the Japanese did copy that particular style from the brits, when Honda and the rest started making "large" motorcycles. But you have to remember that in the late fifties to the early sixties, BSA sold more motorcycles than any manufacturer in the world, and Triumph was close behind. In essence, the British Motorcycle Industry was the standard of the world then, and so Mr.Honda had a large target to shot for, and so most "real" motorcycles that Japan Inc made then had a definate "British look" to them.
Now, with H/Ds being so popular, Japan Inc has switched to the V-Twin as their target, and if the street bikes from Japan aren't repli-racers(sportbikes), there most likely American in style or "Harley Clones" now.
Cheers,
Dwight