The One Death That Stopped Game of Thrones From Going Too Far
Death of Robert Baratheon in Game of Thrones led to a succession of horrifying events – in fact, the majority of bad things which happened in the series were caused by the resulting chain of consequences.
But it also saved Westeros from suffering even more senseless violence and brutality, never mind possible extinction of all life.
While in many aspects Robert was a decent king, he had several crippling flaws, and one of them was unwillingness to confront problems which could not be solved without drastic measures and turmoil (which caused his death to start with).
Had he lived, he probably would still have maintained that Cersei' children are his heirs (remember, while we, the audience, are given Cersei's own admission of her infidelity, in-setting Ned Stark had only very tenuous, indirect proof for his realm-shaking accusation).
And that would have resulted in Joffrey becoming King Joffrey I as soon as fate claims Robert. The book Joffrey was bad enough, a kid drunk on power and thinking that power means cruelty.
The TV show version is even worse, adding all the makings of a genuine serial killer. Joffrey managed to prove himself an exceptionally bad king, despite still not being of age – both in theory and in practice his power was limited by Cersei as Queen Regent and Tywin as Hand of the King (and commander of the actual army, keeping Joffrey on the throne).
He still managed to make several high-impact and disastrous decisions, from ordering Ned's execution to provoking a revolt in King's Landing.
Even other characters have compared him to the Mad King Aerys (and Aerys actually was a charming teen at Joffrey's age).
Without Joffrey outgrowing his impulsive malice, he would have been overthrown quickly, still plunging Westeros into civil strife. And by outgrowing it, he likely would have become a more competent, but extremely cruel tyrant.
Well, and that's without considering the threat of the White Walkers.
The war that Daenerys waged for the throne of the Seven Kingdoms already was brutal, and resulted in her going off the deep end, but at least for a time she was able to see the White Walkers as the real threat.
With Robert still on the throne that could not have happened, given that he hated all Targaryens, and that Daenerys hated him – there could be only a merciless struggle.
So, Robert dying when he did, probably saved Westeros.