Originally posted by Kunzite But I can think of a possible reason: the 70-200 f/4 would work well with a rear converter.
The Ricoh site refers to that as one way to use the new lens. They have sample shots taken with the DFA 70-200 + DA 1.4x TC mounted on a KP:
Featured03?HD PENTAX-D FA 70-210mmF4ED SDM WR? | About HD Coating / Lenses / Products | RICOH IMAGING (ie effectively 280mm f5.6).
For an APS-C photographer wanting to shoot wildlife, it doesn't seem a particularly appealing option. The DA 55-300 PLM (f5.6 at 260mm) would be much cheaper, half the weight and have much faster AF, even if the IQ isn't quite as good. Or the DA*300 f4 would be one stop faster (a big advantage for wildlife), about the same weight and cheaper than the 70-200 + TC combination, with similar IQ, and also with SDM AF.
I guess the appeal of the option of combining the 70-210 with a TC is versatility for people who mainly shoot landscapes or portraits but want the ability to take the occasional large-or-not-too-distant wildlife/animals shots. That was kind of the sell for the DA*60-250 f4 as well, but we don't see many wildlife shots with that lens (with or without TC) on this site. @Normhead used it for that purpose for some time, but these days he seems to prefer his 300 f2.8 (with or without TC) for static situations or the 55-300 PLM for walks.