Why not? It's just an annoyance step that is predicated on obfuscating information that has already been made publicly available.

> Maybe listing shouldn't be enabled even if all the files are public.

I don't see why. Support for firmware upgrades literally involve querying available packages and downloading the latest ones (i.e., apply upgrades). Either you use something like the S3 interface, or you waste your time implementing a clone of what S3 already supports.

Sometimes simple is good, specially when critics can't even provide any concrete criticism.