A:Answer There may indeed be a reason, but if there is, it is probably because of the market being hokey, as it often is.
It does seem strange that these would be less expensive than the slower RAM. The only thing I can think of is that the 3200MHz has faster transmission timings.
That being said, I haven't tested the 3200 and 3600 side-by-side, so I wouldn't even know how much of a difference there would be between them; probably too negligible to even notice, unless in bench-testing.
Nice B-Die RAM though.