This is one issue that already came up on the first review of classical issues in 2014, and was brought up again by @Sophist recently. Currently, works are a flat list, and displayed as such. They aren't exactly flat, in that works can be listed as part of other works, but right now that isn't used for organisation at all.
Displaying works better based on that is something that was requested many years ago, and we should be able to improve that relatively soon. But without an extra level of detail that we currently miss, we wouldn't know what to show in a work list, other than "the top level of the work relationships".
This is not ideal, since it'd mean showing "Piano Sonatas, op. 2" on Beethoven's work list instead of each sonata, which is what a user would expect, or showing "6 Gesänge, op. 34" on Mendelssohn's list instead of the songs.
A suggestion that we've had is to have a field for the work "level" - something like "collection"/"main work"/"part". Is this something that people thing would work? I'm sure there are plenty of edge cases waiting. I'll offer the first: The overture for Mendelssohn's Ein Sommernachtstraum, op. 61 was composed separately as its own work many years before it was included as the overture for the later work.