I agree that a contact sheet would be useful.
I have had a love/hate relationship coming up with workflows that create customized, templated contact or “proof” sheets my entire career, so I have a lot I could say about this.
My $0.2 would include your assumptions, e.g. settings for an adjustable image “grid” layout via columns and rows. And of course metadata captions, page numbers and optional labels like project header. The usual output formats are all a good idea but overall PDF makes the most sense if there is any scannable, indexable, or layered content.
The Adobe suite of products has always done contact sheets in rather clunky, confusing ways. Apple’s Preview can do it with only with image thumbnail grids, with very little layout control and a complete lack of captions like filenames or metadata. Everything is always just missing the mark for ease-of-use or customizable options.
Photoshop’s “Contact Sheet II” tool creates what amounts to a semi-useless bitmapped output file. I say this because the text resolution is fixed and there is no scannable content and I’ve never found this to be very useful for emailing around or archiving information. This seems to be what most designers I work with continue to use, either out of habit or because they haven’t discovered other tools Adobe has created for contact sheets.
Adobe’s Bridge CC does contact sheets to PDF pretty well as the PDF isn’t entirely rasterized. It’s probably the best way to go about it in a dynamic manner since Bridge is essentially a DAM app. But you won’t go far on the Internet before you’ll see how much Adobe users hate Bridge. It’s slow, clunkier than it should be and not very well integrated.
ID’s “ImageCatalog” script makes the most editable source one could ask for — an ID layout with live captions, where I can replace one image later if need be, without having to set up and generate a revised contact sheet when something changes. I don’t expect this with a tool such as Retrobatch. Still, and most importantly I can hack the “ImageCatalog” scripts since oddly they don’t come out-of-the-box able to importing PNG for some inexplicable reason .
You probably see where I’m going from all of the above. None of these is that definitive or all that easy to use. A smart tool that can do what Retrobatch already does while also spitting out some sort of “documentation” in the form of a contact sheet/image catalog, while remembering the users ideal layout settings — without a lot of scripting and research to get rolling — would be pretty much unprecedented for any image software I’ve ever used.
Bonus points for creating an HTML contact sheet/web page option, although I don’t know how many would find that super useful. Still, the year-old CSS Grid Layout specification makes generating a contact sheet layout about as easy as it ever could be, as an HTML responsive/adaptive layout could be templated with a few lines of CSS markup: https://www.youtube.com/watch?v=tFKrK4eAiUQ.