By and large, existing metadata elements (authors, book title, journal title, article title, volume, issue, pagination, etc. etc.) have existed "forever".

What you desire would require new metadata items for publication types concerning scientific reports. Fifteen or 20 years ago (edit: ouch, time flies-- this was in the early 1990s) there was the beginning of a discussion on this topic -- it may have involved the Cochrane group and others. (I was briefly involved as a stakeholder with the US CDC Community Preventive Services group where this was discussed.) There were big plans for establishing standard data definitions (study design labels, study population group labels, instrument type labels, labels for statistical tests used, level-of-evidence, etc. Discussions began to develop research term standards across many of the worlds languages. Things fell apart as input was requested from publishers, journal editors, etc. Consensus across disciplines (hard science, engineering, medical-clinical, psychology, sociology, social work) couldn't be reached about which things were important for inclusion much less about how the elements should be defined. There were concerns about how this new 'stuff' would be included with each published report -- how much page space would be allocated. Librarians worried about how this would affect cataloging. It was librarians who raised the questions about how new study-design labels would be added and what would be the process for formal acceptance. People expressed concerns about whether this would be only prospective after a particular date or if there might be attempts to fund a retrospective assignment. Comments were made questioning who would assign the labels -- certainly not the authors themselves when considering the awful quality of author assigned keywords. Questions were raised about taxonomic hierarchies and fall-backs for the metadata items....

I hope this explains the difficulty in implementing your idea.