indexes

I notice a lot of places where people use the approach of creating an index and
a unique key like:

CREATE TABLE foo (
   idx SERIAL PRIMARY KEY,
   name varchar(32) UNIQUE NOT NULL
)

instead of
CREATE TABLE foo (
   name varchar(32) PRIMARY KEY
)

If the name is NEVER going to change, is there any advantage to doing this?
If there are many-to-many reference tables (like name-to-friends) is this any
different?

I've seen this a lot, but I've always assumed that with the condition that
'name' would NEVER change, there was no advantage.