The whole premise that KC is some regular 'dad', as OP says, is totally unrealistic. He's now the Head of State and was for years second in the royal hierarchy. His chances of being a 'great dad' are on a par with the CEO of a multi-national company or similar.
I think he's a decent man who tries to do the right thing. He's made mistakes - but when will simple-minded folk stop beating him with the 'he betrayed our darling Diana' stick. Loads of marriages and relationships fail - theirs failed for complex reasons and not just because of Camilla. Let's not keep bringing that up - I feel sorry for both parties in the marriage - oh, and Camilla too.
I think Harry was spoilt by Diana - she admitted it, pretty much. Her advice to him was 'If you're going to be bad, just don't get found out!'
Saint Diana of Althorp wasn't a great mum, actually. She spent a lot of time away from 'her boys' in the last period of her life while chasing dodgy men. If you want to find parental blame for the patheticness of Harry, you have to admit Diana was no model mother either.