What is the moral of The Death of Ivan Ilyich?

I think, in answering this question, it's useful to consider how this story is structured, because The Death of Ivan Ilyich begins at the end, after its protagonist has died, with Ivan Ilyich's funeral. In a way, then, it might be useful to consider the funeral scene itself and how it relates to the larger story that follows.
In the funeral scene, what we see is a focus on appearances. Ilyich's friend Ivanovich (whose viewpoint we initially follow) is largely focused on giving an appropriate impression. You see this in his continued observance of the signing of the cross (which is joined with his internal preoccupation concerning the appropriateness of the gesture) or in his greeting the widow, Praskovya, who is herself primarily interested in maximizing the amount of money she can receive from the State, now that her husband is deceased. In reading this scene, you might get a sense of artificiality on the part of its participants and, ultimately. dishonesty.
From here, we follow Ivan Ilyich, starting in his youth and carrying on until his death, mirroring the funeral scene itself. We find that for much of his life, Ilyich had possessed a single minded focus on appearances. However, as his illness takes root, he comes to realize just how hollow (and ultimately meaningless) his entire life had been, and as his illness worsens, his despair only grows. What we see in Ivan Ilyich is a condemnation of the materialistic lifestyle, which provides no comfort in the presence of death.

The ultimate moral of the story is that life without love is unsatisfying and meaningless. Before his last days, Ivan was driven by material and social success. He married for social and economic reasons, never truly loving his wife. He worked only to get more furniture and goods. However, none of this ever made him happy.
So, when he realizes he is dying, he is distraught, even angry, at this twist of fate. Then he comes to regret that he did not love more. He feels pity for those consumed by egotistical desires that will never satisfy them.
Once Ivan starts thinking about others and loving them, he becomes happier in his final moments than he ever was in his "healthy" days. Even though his body is failing him, his soul has never been more alive. The people around him who have not yet awakened to his great lesson are more to be pitied than he—at least, that's what Tolstoy's text appears to suggest.

The message of The Death of Ivan Ilyich is simple. Ilyich was living the wrong life when he was thinking about his own selfish ego, and he was living the right life when he began thinking about others. His ordeal was a learning experience. The Death of Ivan Ilyich is similar to Charles Dickens’ A Christmas Carol. Scrooge becomes enlightened and happy when he stops thinking selfishly and begins thinking altruistically.