Sorry, it's easy to forget what the commodity prices of some of the Azure DevOps tools are given that various combinations of MSDN licenses and Office 365 plans cover them. It's great that you can pick and choose now, though.

Like I said, caching is only a useful side effect of Artifacts for npm and NuGet users (that have access to Artifacts). I would believe/hope that Microsoft may still have interest in adding proper caching to Azure Pipelines directly.