What did people do when there was no recently deleted folder?
The way TiVo handles recordings hasn't changed. Even though a show is deleted, the data remains on the hard drive until it is overwritten. With the addition of the RDF, TiVo allowed us access to that data.
People who 'permanently delete' shows from the RDF are only satisfying their OCD urges (IMO). All they are doing is putting their Tivo in a pre RDF state. The data is still on the hard drive, only the Tivo has marked it as 'permanently deleted' and it is no longer accessible.
I admit that I (with my OCD urges) micromanage my Tivos to make sure they are recording what they are supposed to be recording, but never have I had the urge to clear out the RDF.
Edit: Or what scandia101 said.