If anything, LCD probably lowers the cost of the machine to the manufacturer. It's obvious an LCD screen is cheaper than a DMD, and I would also doubt that programming for it is any more expensive -- video editors and digital graphic artists are ubiquitous and tend to skew young. They're a dime a dozen, and can use any major industry standard tools to do the video. Meanwhile, people who can do DMD art are much less common and probably more senior members of the industry, and need knowledge of proprietary software. in other words more expensive.
anyway, it's not like Stern wasn't making severely minimalistic playfields before the LCD anyway.