Why Angel, Dennnis, and Rocky were so integral to the show....
They showed how Rockford was different. A man who could have a friendship/relationship with men so different from one another.
Rocky is old fashioned, honorable, "country strong" and fairly naive when it comes to con men, crooked police, etc. Rockford is much more savvy. But he is honorable and loyal as well just like rocky
Rockford can be a world class con man at times, but he is nothing like angel - a con man with no spine, loyalty or conscience. His loyalty to angel despite angel's disloyal nature shows his character. I loved this relarionship because it was like an older brother and his troublesome younger brother.
Dennis is law and order. Jim does a lot to get on the wrong side of cops, but at the end of the day he and Dennis always end up as allies. This is maybe the best relarionship on the show, because it shows hke Rockford can do things cops can't and vice versa.