i actually happen to agree with you that the Orient 300M diver is a superb value and offers a lot of bang for the buck. by rights, Orient should be charging more. the fact that they don't is partly due to (customer perceived) image & branding.
i think someone would be hard-pressed to find a swiss-made diver that competes well against the MM in the major categories and i find it rather ironic that a favorable contender to the MM would come from Orient, a company that is partly owned by Seiko and which is able to leverage some of the benefits of this Seiko partnership such as the MM bracelet and clasp influencing the one offered w/the Orient diver.
one of the drawbacks to the Orient is the non-hackable, non winding movement. it may not be that significant to you but for others it is significant as seen by a number of posts here on WUS.
but the difference in movement is one of the reasons why there is such a big price difference between the Orient and the MM, much as the co-axial in the PO puts it at $1000 more than the SeMP. there are obvious differences in cost of manufacturing and yeah, the 'in-house card' does get played as justification for higher pricing...that's the nature of the game.