Which Character Suffered More in Richie's Absence?
To me, it's a toss up between Lori Beth and Potsie. Both characters needed to have Richie around to play off of to really work. After Ron Howard left, it seemed like they only really used Lori Beth for "ghost" storylines involving Richie (like their "wedding" and the birth of their son). I also found it funny that Richie wasn't allowed to be at least temporarily discharged from the Army so that he could be there for his son's birth (it kind of made Richie look bad if you asked me).
With Potsie, I honestly don't know why Anson Williams stayed on after Ron Howard and Donny Most left. The writers didn't really know what to do with Potsie. All of the "youth" storylines that Potsie, Richie and Ralph once occupied were now transferred to Joanie, Chachi and Jenny (and to a lesser extent, the students that Foznie and Roger taught at Jefferson High). I think there was a period where they tried to make him into the Cunningham's surrogate son in Richie's absence (like having Potsie work at Howard's hardware store).