The importance of handwashing can't be overstated, it is one of the keystones of sanitation and public health! Hospital transmitted infections would go way down if staff followed all checklists to a T.

It's a matter of defense-in-depth. When the traffic is heavy enough to have less than 5 minutes between contacts, how many more people would be infected after a week?

As for cost, it would be more expensive but less so than you might think. With how thin the plating layer is, even for heavy wear, the material cost is under $500 per square meter. For small objects like buttons, door knobs, and hand rails it's negligible compared to installation and other costs. By switching to a cheaper base material it could even be cheaper over all.