> why move onto something even more advanced.

Because the SATA cable is neater. In particular eSATA is neater than PATA in an external enclosure.

While there are lots of existing USB enclosures and few eSATA ports about, this isn't a particularly compelling reason, but if a SATA connection can be built for around the same price as PATA, I'd expect the trend to be towards it even for optical drives.