The ability to edit custom value keys like you can in custom fields.
Our current use case is a branding issue. (Im sure there are other more usefull use-cases other than vanity).
Our naming convention for a snapshot included "Pro" in it, and we branded away from "Pro". We were able to edit everything except for custom value keys. So the custom values used to say "Pro Offer", now it says "Offer", but the value key itself is still {{custom_values.pro_offer}}.
This affects our training we create because as we document and train how to use the snapshot we have to explain-away why it says "pro" and not just "offer".
Another issue is if we were to rebuild the custom values, it would mean that we need to also update the hundreds of emails and texts where those values exist as well.
This would be a nice quality of life feature for custom values.