I think the show is great. However I don’t think the characters optimism is his defining feature. His best feature is that he knows how to bring out the best in others and wants that for them. That’s what really sells the show - his sincerity and the thought the character gives to actually helping people be better. But the show also works because the other characters are amazing. And interestingly all characters act like real people. There is not a lot of artificial drama for the shows sake which is a a welcome relief.