I don’t see a big problem with the current handling of digital releases on MB. At the moment we make a new release if there is some difference between cover art, titles or the audio itself (mastering etc.). If there are clear differences in bonus content (PDFs or something), I’d think of making a new release too.
As you said barcodes are not always available or not used to differentiate releases in the digital world. As useless as they are most of the time, being able to add multiple barcodes to digital releases would be nice though: MBS-3978.
I can find two reasons on behalf of a reform: releases being packaged in different audio formats and releases being distributed to different digital stores at different times.
About audio formats. I see how it would be useful to know when an album was released in a higher quality than before. For example, an album was released as MP3 128kbps in 2011, as AAC 256kbps in 2012 and as 16-bit FLAC in 2013. There are some problems with this however. Would 320kbps MP3s released in 2014 require yet another release? If yes, that would open up an ultimate mess of digital releases which would be useful to no one. If no and the 2014 MP3 was merged with the previous MP3, we would leave a huge quality difference in the MP3 release page.
Would a FLAC album share its MB release page with an ALAC version since both are lossless and they can be converted back and forth? Actually once an album has been released in a lossless format, no more lossy releases should be made since the lossless files can be transcoded into any of those lossy formats. What should be done if the FLAC was a transcode from a lossy format and actually not of great quality?
I say no to separating digital releases based on file formats or audio quality. If we want something like this, adding a file format selector to “purchase for download” links would be one way to go in my opinion. However, selecting a quality could be misleading: of course we trust that stores give us files which are not lossy to lossless transcodes but that may not be the case with sites like Bandcamp for example.
About release dates on digital releases. I think there is only one date which is important enough to be highlighted in a digital release and that is the first time the release was made available in a digital format. Let’s say a new digital store pops up in 20 years and it starts selling Beatles albums. I’d still link them to old MB releases even though the store would probably have a new “release date” for the albums. The new date could be added to at least two places: on the store link itself and on a distributor relationship. Over the years there can be multiple stores and multiple distributors but handling that is no problem for MB even today.
Edit: One thing worth to point out is that we don’t have proper tools to mark which countries an album is available in for stores like itunes. That will definitely get messier over the years if there are multiple stores which all have different kinds of area restrictions. Also it’s a job for automated scripts, checking country limitations manually is too slow to even consider.
Edit2: something something