I don't know that Oracle thinks it is a bad thing, they just choose to solve the problem a different way--with "sequences". In Oracle, as you may know, a sequence is it's own thing outside of any table. Personally, I wish the databases I work with had both an autonumber/identity and a feature like a sequence. They are both very handy. A sequence can be useful if you need a way to have an id unique across multiple tables or multiple databases.

It's easy enough to code your own sequence-like feature using a one column/one row table and a function, but I assume Oracle's sequence feature is highly optimized to do what it does.