The advantage to this approach is if you have several machines on your lan and you use a single caching nameserver, then your other hosts can query your caching nameserver host and aggregate calls to the remote servers while taking advantage of the caching service.
On a network with restricted access to the Internet, this makes sense, as you reduce the use of the scare resource, your small pipe. For a machine with a broadband or better connection, you would suffer the cost of the extra hop going through a forwarder if there's a cache miss, which makes performance highly dependent on the characteristics of your forwarder's cache. It also makes you vulnerable to misconfiguration of the forwarder. (Ask Comcast/ATTBI customers about that when it happened a couple years ago for a couple months and screwed up Win2k users. Win2k's client caching resolver locks to the first server returning a reply, and it would randomly lock to ATTBI servers with bad information.) A root hints system removes your forwarders as points of failure. You bypass them and go straight to the authoritative servers for each domain.
