It’s a pretty good point. Though, if you didn’t have Vault-Key combo you would want Voltaic Key just to make Wishclaw Talisman more powerful. And then by having Keys and Wishclaw you might as well play Time Vault. I suspect the dual tutor might be more instrumental in setting up Bolas, Karn, or Mystic Forge possibly if Time Vault wasn’t an option.
Or in a Ritual or Belcher version there might be more lines to take with it. Though I still think you play Time Vault.