...I would have thought there's credibility in owning the top end of the market.
I don't disagree. I think it's just a question of what that credibility might be worth...especially during difficult economic times.
How many people buy DSLRs based on the top-end? How many care what name plate is on the big white lenses and brick-like bodies at sporting events? How many bought Canon equipment because they saw Art Wolfe on TV? A few maybe, but not many. More likely the choice is made based on what "celebrities" pitch, and and what their friends shoot. Mercedes Benz could not expect much from the name if they got into the budget car market.
I would think the opposite! A mid priced Merc would sell well IMHO.