I mean, I'm disappointed too, but it happens. It's a physically demanding show, and I'm sure that JCM would rather take the time to properly heal than risk cancelling more performances. And it's not like MCH is some nobody- I exchanged my tickets, but if for some reason I'm sure I'd still enjoy his performance.
I am a firm believer in serendipity- all the random pieces coming together in one wonderful moment, when suddenly you see what their purpose was all along.