I think the Potsie character suffered greatly due to the departure not only of Ritchie but Ralph as well. The writers had no idea what to do with Potsie once Ritchie and Ralph were no longer there for him to interact with. And it seems like didn't really try either. It seems like the writers choose to concentrate on Joannie and Chachi and the newer/younger characters and Potsie and Loribeth just faded into the background.
Only a life lived for others is worth living. Albert Einstein
A life isn't worth living unless it has impact on other lives. Jackie Robinson
Be always at war with your vices, at peace with your neighbors, and let each new year find you a better man. Benjamin Franklin