Skerritt was actually the one who had the better profile recognition among mainstream audiences at the time, yeah (not nearly so much now, but back then). That was part of the genius in killing Dallas off so early.
Viewers, today, don't understand how much of a table-flip that was. Audiences expected him to be the one to survive, not just because he was a male and in charge of the ship, but because of the actor. When he died, effectively all bets were off.