[dianebrat]

It could be a case of adding new features required eliminating some lesser-used features. Given strapped resources, the firmware can’t offer an endlessly growing feature set.

I would also say that there's a good possibility there was a security vulnerability in the code library that the Tivo and DLNA shared and it wasn't worth the time to redo it, so they deleted it for safety.
I say this because the Tivo Backup code in the ReadyNAS line is part of the DLNA package.