They are really designed with different needs in mind. Code in object types are related to the OO programming model, where we have methods and constructors that pertain to the object itself.

Code in packages might pertain to something totally independent of any form of object, or even a database table. For example, dbms_output is for putting output back to the client.

Obviously, anything you can code in a procedural model, you could transpose to an object paradigm, and vice-versa. eg, UTL_FILE for file I/O could easily be converted into a type where a "file" is the object, and the methods are there for opening/writing etc.

There is nothing to stop you from getting the benefits of both. For example, we have many "procedural" packages that use XMLType, which in itself is a type that takes advantage of the methods/constructors

Hope this helps.