I have seen numerous mentions of the Four Thirds format dSLR cameras being less than optimally proportioned for landscape photography.
Firstly, Pentax is probably limited to using existing MF sensors in the catalogs of Kodak and Dalsa, all of which are 4:3 except the one larger, more expensive 55MP Dalsa. Leica has paid extra for a special 45x30mm sensor, but for wider panoramic landscape shapes that only gives 1mm more width than the Pentax 44x33mm, so it hardly seems worth the higher cost of a custom sensor! Cropping 44x33mm to 44x29.3mm gives 3:2 when you want it.
Secondly, the idea that a 3:2 format camera is better than 4:3 for those interested in landscapes is a bit of a myth, and hard to reconcile with all the great landscape photographers who have chosen large format and medium format gear with formats like 10"x8", 5"x4" 56x56mm (6x6), 56x42mm (645), 70x56mm (7x6), 75x56mm (8x6) and so on. None of these is wider the 4:3 and most are squarer. The only 3:2 or wider formats I know of in MF or LF film were always uncommon, like 9x6 and 17x6.
The idea that 4:3 is a bad gear choice for landscape photographers seems to turn on two fallacies:1. People who are interested in landscapes have little or no interest in any other subject matter.
Instead, I am sure than many MF users including Pentax 645 users also photograph many urban scenes, portraits, interior scenes, and nature scenes at closer range than stereotypical landscapes: trees, flowers and such.2. All landscapes are sweeping panoramas with wide, low horizons.
Instead, landscapes often feature strong vertical elements from mountains, trees and so on. Some famous Ansel Adams landscapes are verticals, and many fill the height of a 10x8 frame and would suffer badly from cropping to a wider, lower shape. Since we are talking about the Japanese market only for now, perhaps we should study images of Mount Fuji for shape preferences!
Once you look at the overall balance of composition that users are likely to be interested in, the case for inferiority of 4:3 (and more so the classic 5:4 shape of most large format and also of "7x6" MF) become very unclear.