Thank you for your feedback. We are currently in public preview of blob storage lifecycle management. The feature set offers a rich, rule-based policy engine which you can use to transition your data to the best access tier and to expire data at the end of its lifecycle. See our post on the Azure Blog to get started: https://azure.microsoft.com/en-us/blog/azure-blob-storage-lifecycle-management-public-preview/preview/.
For any further questions, or to discuss your specific scenario, send us an email at DLMFeedback@microsoft.com.
Quick update: We reduced the entry point to partitioned collections by 75% to make it more cost effective for applications that need high storage but low throughput.
Please see https://azure.microsoft.com/en-us/blog/azure-documentdb-entry-point-for-partitioned-collections-now-75-cheaper/ for details, and email us at email@example.com for any questions.
This would be awesome to have!