Currently, the Devices spec uses ByteStrings to provide Icons and other support files.
That works fine as long as ByteString is small. For larger files, the access becomes more complicated, and in general, we introduced the file transfer for that scenario.

In the Harmonization WG we reviewed the latest FDT spec, which uses the Devices spec in many places but uses file transfer for files instead of the Devices solution.

It might be reasonable to add the capabiliies for file transfer in the Devices spec as well in case other CS want to use files because in there scenario those files become large as well.