From Overview of JDBC and its use with CORBA or Java RMI CPS616 Technologies of Information Age -- Spring 1998. byNancy McCracken(Sangetta Aggarwal, Udayan Parvate, Tom Pulikal)
Advantages are :
avoids installations of any vendor specific libraries at the client side
uses general client/server solutions for distributed systems over the Internet/Intranet
From now on, we follow common practice to also call the 2+ tier architecture, a 3 tier architecture.