The increased focus on data management planning began in early 2011, when the National Science Foundation in the US began requiring DMPs with all proposals.
From the National Science Foundation:
Beginning January 18, 2011, proposals submitted to NSF must include a supplementary document of no more than two pages labeled "Data Management Plan" (DMP) . This supplementary document should describe how the proposal will conform to NSF policy on the dissemination and sharing of research results. Proposals that do not include a DMP will not be able to be submitted. For more information about this new requirement, please see the Grant Proposal Guide, Chapter II.C.2.j and the Data Management and Sharing Frequently Asked Questions(FAQs).