Mike, I think that Ruger could make the trigger 60% to 75% better with nothing more than a lighter spring and would cost them virtually nothing extra since they need to put a spring in anyway. A spring alone might not be a substitute for the Volquartsen accuracy kit but it would be a vast improvement over what currently comes out of the box now. While I have not yet measured the trigger pull on her pistol, I'd venture to say it is between 4.75 - 5.25 pounds. IMHO a "target pistol" should be between 2.25 - 3 pounds and crisp with no creep.
I also agree that their standard model which is not sold as a target grade model might be acceptable with that kind of trigger pull, but a pistol that is engraved and sold as a target pistol should at least have a trigger worthy of that name.
If I owned Ruger, I would offer a Volquartsen kit already installed in the pistol and charge let's say $100 bucks more for it. Volquartsen wouldn't charge them anywheres near the same for thousands of them as they do us for just one. This way it's a winner right out of the box.
IMHO Ruger does this for two reasons. To your point, they save a few penny's but the main reason is more than likely for liability issues. This way someone converting it to a target grade trigger has the liability on Volquartsen and themselves as the owner. If they continue to do this, I would suggest they stop roll marking the barrel "Target Pistol"!
I'd venture to say not many people use a Ruger Mark 4 .22 pistol for CCW, EDC or SD /HD purposes and so the only place these 22's are actually loaded is when on a Range. There is probably little risk in making the trigger "target worthy" and as all of us know, no matter what the trigger pull is (light or heavy) there will always be some Bozo who does something stupid. Like they say in Forest Gump, "you can't fix stupid" no matter how light, heavy or creepy a trigger is. Again, keep the regular production trigger on their standard models - but at least give the marked Target Pistols a descent one.