[Brightcolours]

I suppose because economic 90~105mm macro lenses are plentiful (K, F, screw, etc) and easy to adapt to u4/3. (And for macro work, manual focus/diaphragm are acceptable.  The same cannot be said of 30 or 60mm.

Hmmm, actually 50mm and 55mm macro lenses are plentiful too (F-mount, K-mount, M42, FD-mount, EOS mount, different Minolta mounts)

I doubt that Olympus/Panasonic actually don't want to sell you a new lens because the customer can go elsewhere for old lenses?