First of all, Larry King was never really good at being on television. He was, when he was in radio, one of the best radio talk show hosts in America, practically owning late night and well within his limits in that medium. On television, he was adequate but never incisive. He never asked the question you wanted to have answered and he fawned over guests that should have been handled by a better interviewer. CNN should have replaced him a full decade ago.
Piers Morgan is a newspaperman from England--which is eerily similar to being a fox assigned to make sure the hens are completely safe and accounted for in a tawdry henhouse. To be a newspaperman from the British Isles is to be wholly without ethics or accountability, and that describes Morgan perfectly. He was entirely out of his element on American television.
That's why Morgan is eminently qualified to be the editor of the National Enquirer and not much else. This is not about Americans rejecting a pompous Brit--we love the Brits when they're pompous and we embrace the good ones for decades. Morgan simply should not be on television. He needs to go home and admit that he was a phone hacking, ethically-challenged pseudo-journalist and beg the British people to let him be a weekend presenter on a channel no one watches.
His opinions really didn't matter. No one is expecting to tune in and see an incisive debate on American gun control anyway. Why would you tune into an opinion show on CNN and expect a hard right wing viewpoint every night? This did not sink him. His intelligence did not work against him. His inability to become a television news channel broadcaster doomed him.
CNN made a terrible choice in hiring him. They made an ever worse choice in waiting to see if he would catch on. The entire management team at CNN is exactly who you'd want running a money-losing fiasco.