I have several old shotguns with less than pretty bores. They all shoot quite decent patterns, one gives excellent (even) patterns.
SO long as there are no deep pitts that are serious weak points, especially near where my forehand is, I no longer concern myself with them.
The other non-cosmetic concern is that baddly pitted bores are harder to clean than nice shiny bores. With nitro powders I don't worry much, but, I do keep such bores well coated with a nice penetrating oil, RemOil for me. With BP, I get lots more concerned and mostly do not shoot BP in guns with pitted bores.
Niklas