Interesting question. I guess the answer is six of one and half a dozen of the other.

With regard to parameter tables in particular I always tend to give these an Identity column as a Primary Key. Why? well firstly it's safer to be very clear about which parameter you want to use and an identity is potentially a lot clearer and simpler than say a Varchar. Secondly, my coroporation's standards often put parameter tables on linked servers plus parameters can be updatable by applications, we've had some probs with DML between linked servers where there isn't a unique key on a table.

I have found it is possible to please all of the people all of the time if you do exactly what they want. Harold Macmillan 1961