The new Microsoft Graph reporting API is now general available. This API allows customers to obtain richer access to usage information in their environment. Since this created some overlap with exist...
Updated Dec 22, 2017
Version 4.0
Blog Post
Jeff Brown, sorry for the late response. You are correct, currently this data is not exposed through API, but long term the team wants to address it. In the meantime it is always a good idea to leave feedback on https://microsoftteams.uservoice.com/forums/555103-public