Guys, the point is, Sony REFUSED to put a large sensor in something like an EX1 body precisely BECAUSE they were trying to protect their super-expensive Genesis, F23, etc. They withheld that technology from prosumer shooters so as not to undercut their ultra-expensive cameras. That is the whole point of this entire discussion.
Or because the cost for silicon wafers of that size have been expensive-as-balls up until recently...
but it's probably a mix of both.