Thanks Arlo! I think that will be helpful when editing a preset, particularly to avoid tricky maintanance issues where a preset is used by both a song and also by other presets.
Short additional response: For my use case (which is probably an outlier!), I'm probably better off just maintaining a spreadsheet to document song / preset usage.
Longer explanation, if interested in the use case:
I've now made heavy use of BH's recursive MIDI preset inclusion ability, down to three levels in some cases. I've found it to be a great tool for organizing these presets into easily manageable groups for controlling my mixer, keyboards, and guitar effects (particularly since many changes involve multiple CCs and/or PCs to get the job done, including nuances like temporary volume & effects changes for the guitar.).
I've evolved to just maintaining a separate spreadsheet to document which songs use which presets, so there's less of a need to see what songs use what presets in BH. I can sort my spreadsheet by guitar preset to see what songs might be affected if I tweak a particular presets, or sort by song to see what presets a song will use.
So the capability that would really replace what I'm maintaining by spreadsheet would be to completely recurse / expand all the presets used by each song and list them in the main MIDI Presets web page, in the Songs column. (Before I started using heavy preset recursion, I used to scrape that page and plop it into a spreadsheet, which worked very well.)
Moreover, I sometimes leave a preset included as part of a song definition in case I might want to use it in the future, but not currently reference that preset in the song's automation. (That reduces the steps involved in adding into the automation if I choose to do so later.) So there would also be value in excluding such presets (those referenced in the song definition, but not actually used in the song's automation) from the list.
I don't expect many others to be interested in something this complex to implement, so I'll stick with maintaining my spreadsheet!

Nevertheless, thanks for listening, and I do think this recent change will be helpful to me and others.
PS: This triggered another thought about making it easier to add a preset to automation, which I'll start as a new thread...