That ending is something that my brother and I reference today as an example of how art can become top-heavy and unconvincing (The sun is the "source," which in this case is the father, who has passed his disease literally and figuratively on to his son).
The ultimate problem I have with Ibsen is that his plays feel pre-configured, even fake. He's never searching for a thesis or questioning. He has an opinion to unload (e.g. the sins of the father shall be visited upon the son) and he's decided to use a play to do it. The result feels sterile, boring, lacking in wit, pointless.
I would unfavorably compare Ibsen to Raymond Carver. Carver also deals with disintegrating families, marital tension, poverty, alcoholism and the rest. But Carver somehow feels vital and real. His writing never resembles overwrought tragedy even though there's plenty of unhappiness. You never get the feeling that Carver has the answers or that he's talking down to you.