Mh, perhaps because it's human? It's actually not that far off from reality. For a long time men were providers and didn't really need to be there for child raising at all. It is/was a socially acceptable way.
And being a workaholic and burn out are also quite common problems on many people.
At least he acknowledged his failures and when given a second chance with his daughter, actually tried to work on their relationship. That's more than a lot more than a lot of real people are willing to do. Not just saying "the other's are at fault" but actually seeing the problems realistically, that does need courage and is not something many people are able to do.
So in my opinion, even if I can relate that he wasn't the best at being a dad, I can acknowledge the work he put into trying to work on it, when given the chance and having reflected on it before. It will never make it all go away or fix it, but it's at least an effort not everyone would be willing to do.
I don't care about the age gap as much as I care about the dude being a deadbeat father. His daughter's memories of him are mostly of her parents fighting, he says he didn't love his family anymore, never cared to rekindle with his daughter and it only happens because she initiates it... Honestly why would I root for someone like this?