For a generic volume manager, it would be useful to be able to get a unique identifier for a volume that will be persistent across device insertions/removals (e.g., to allow the volume manager to remember an action to take when a specific USB key is plugged in). HAL provides this via libhal_volume_get_uuid(); not sure how to implement this for other backends. Volume labels (and thus the value of thunar_vfs_volume_get_name()) can change, and mount points can change, so these two options aren't ideal.
I think you're somewhat beyond of what thunar-vfs should provide. Why not simply use HAL directly?
Well, a couple reasons: 1. I know thunar-vfs' API, and it provides (almost!) everything I need. I only know HAL superficially, mainly just from digging around in thunar-vfs. While learning HAL probably wouldn't be a bad idea, I have better uses for my time right now (like actually writing code). 2. Using HAL directly, I'd be duplicating a decent amount of code you've already written. Seems like this would be somewhat error-prone, and I'd miss out on your experience with HAL. (I guess likely I'd end up copying portions of thunar-vfs and stripping it down, while adding extra features I need, like UUIDs.) 3. I wanted to see if I could get something working pretty quickly. I don't have a lot of spare time for OSS work lately, and using an existing framework seemed like a good idea. If you still think I should just use HAL myself, let me know, and I'll implement this without the ease of thunar-vfs. Just it'll take me much longer to get this working, as my time is already pretty limited, and I'll essentially be reinventing the wheel. I certainly understand if this type of thing is a bit out of scope for thunar-vfs, though.
I guess this can be set to WONTFIX then.