What pain and suffering can be inferred from the dollar amount of medical bills

In Barkley v. Wallace, decided on Friday, the majority of the Virginia Supreme Court in an opinion by Justice Keenan held that it was reversible for the trial court in a personal injury case to exclude evidence of the amount of plaintiff's medical bills, where the plaintiff claimed the dollar number would be introduced for the limited purpose of confirming the plaintiff's pain and suffering. The Court split 4-3 on the question of whether the trial court's error was harmless, with Justices Lacy and Agee joining the dissent of Justice Kinser, who concluded the error was harmless because the plaintiff introduced other evidence on the issue and the exclusion of the cumulate evidence could not have affected the verdict.

It is not that clear to me that there is much of a connection between what medical services cost (as opposed to other facts about the medical services) and the amount of pain and suffering. That's sort of like trying to guess how far did you go on a commercial flight based on the cost of the plane ticket - there might be a connection, but then again, there might not. (The flight to Philadelphia last month cost almost $800!)