Why does Oracle not support an autonumber data type? I know that Oracle implements autonumber functionality using sequences and triggers, but why doesn't it have a built-in autonumber data type as do most relational DBMSs? There are two specific parts to my question:


I know that sequences with triggers are generally more flexible than what autonumber fields in other DBMSs provide. However, what are the some particularly superior features of Oracle's implementation?
Considering that autonumber for primary key attributes is such a universal use case, what is the disadvantage of implementing it that keeps Oracle from adding such built-in functionality? After all, they can still keep sequences and triggers with any additional features they might provide.


I know that this question might be difficult, since it is not a "how-to" question but rather a question asking background behind Oracle's design decisions for their DBMS. However, I feel there is much to be learnt in understanding Oracle's thinking in this matter.
Well it does now - Oracle 12c introduced IDENTITY columns, see:

Identity Columns in Oracle Database 12c Release 1 (12.1)

e.g.

CREATE TABLE identity_test_tab (
   id          NUMBER GENERATED ALWAYS AS IDENTITY,
   description VARCHAR2(30)
);