I would argue AC+ protects things that are more relevant than a case can provide. It even include free battery replacement within the coverage period, which we know will be degraded in 2 years. Also if there’s any physics damage just pay $29 and you get a replacement refurbished unit which will be like new. No one knows how the mesh headband will hold up in 2 years either. Seems a better way to spend $60 upfront and not have to even worry about having to use a case in the next 2 years.AC+ does not protect against everything. Listed under exclusions: "cosmetic damage not affecting the functionality of the Covered Equipment."
So dings or scratches as result of not having a good case would not be covered.
For example, for Apple watches, people have discovered to their chagrin that scratched watch faces are not covered by AC+.