I simply cannot refrain from putting this link up:
“Big Two” continue to stomp Digital SLR market in Japan - SlashGear
Although the overall market share numbers are not too great for Pentax, the actual fact is that the only full-frame body on the list, surpassing 1% of the market share is the D700.
Therefore, the full-frame cameras in total amount to a maximum of 2% of the market.
If you are a camera manufacturer, would you strive to get attention of the 2% of the market, or the rest of the 98% of the currently APS-C dominated market?
The qualities of full frame are indisputable. However these qualities yet come at a significant production price. If pentax would be able to produce a FF DSLR at the cost of a mid-range DSLR such as the K20D, it would be a smash hit. This is, however, highly unlikely.
This thread, although criticized as "rabble-rousing" and "red herring" has given me the opportunity to learn some new stuff.. and one is definitely the scale between the APS-C and FF sensors.
From the same wafer, 200 APS-C sensors can be extracted. or 20 full frames, with much more wasted wafer area.
Bigger area of FF means also they will be more likely to "catch" more errors in the wafer. Hence lesser yield percentage.
In the end, FF sensors are too big for most of the silicon foundry production lines around to manufacture without special "stitching" procedures. Hence the cost multiplies.
(In the two links below can be seen an interesting detail: artifacts on the Nikon D3 sensor related to the procedure of "stitching" the sensor parts together in the production,and its apparent effect on the sensor behavior)
Chipworks Behaviour of Nikon D3 at saturation
The bottom line is: full frame sensors are still expensive stuff, and exclusive stuff.
It seems to me fairly obvious that Canon and Nikon's full frame flagship cameras do not pay off on their own, yet they need to exist in order to satisfy the need of the pro consumers, and sell the lenses. It is the bulk of the APS-C DSLRs and compacts that fuels the FF development.
Therefore, I hope to see a lot of APS-C pentax DSLRs sold. That's, IMHO, the only way we will one day see a FF pentax.