The cost is killer, but the bugs really hurt too. We've been talking to Stern for weeks about our Star Wars losing monitor image after being on for 24 hours or so. They keep giving us code updates that don't work. It's a good location, for a pin, but we're losing money when a brand new machine is broken. Plus, it looks bad for the company when games are down.
That being said, I think two color games would be a terrible idea. Like it or not, I think the casual customer is attracted to the IP as much as anything. I'm sure the Star Wars license was expensive as heck, but people love hearing Yoda's voice. There just isn't a magic solution to make pinballs really profitable. People will go either for what the recognize, what's big and flashy, or what they can win a prize with. Pins don't really fit any of those descriptors without a big name IP.