Prince Dickweed really looks tearyeyed at his “fathers” deadbed. 
It was Robert’s Rebellion, after all. The other lords were unlikely to accept Jaimie.
I don’t know if it comes across in the series, but Jaimie is rather stained by the fact that he was the one who killed the Mad King. Not that many begrudged his death, but Jaimie was a member of his personal bodyguard. It’s like the president being taken out by a Secret Service agent.
Yeah that interaction is much clearer in the book than in what I’ve seen in the series.