I don’t personally see any gain from having this data in the medium field which we don’t already gain by the URL relationships for any such streaming page, store page, etc…
if you could select both, I wouldn’t have an issue with denoting a release as streaming and/or downloadable. that said, with how medium types currently work, I don’t see a way of making that work, unless we add three new types (streaming, download, and streaming/download)
another (perhaps better) solution would be to simply use the already existing “Purchase for download”, “Download for free”, “Streaming page”, and “Stream for free” relationships, and make those more visible on the release group page? kinda like @teethfairy mentioned above
for what it’s worth, Rate Your Music handles this quite well with a couple checkboxes. however, they’ve got a very different setup for medium types and whatnot…
like what sort of details, besides the ones mentioned above?
if we do subdivide Digital Media, I suppose I could maybe see options for lossy, lossless, and high-resolution, but it has been discussed elsewhere that it can be difficult to seperate these three (and I think a recent consensus is to merge high-res releases with other digital media releases as mentioned here and elsewhere on the forums)
all that said, I think how it’s currently handled is perfectly sufficient for how I use MusicBrainz (save for making whether a release is downloadable more visible)
to answer the question in the topic title, I think digital media works fine, but online distribution or digital distribution could be acceptable alternatives…