This show has always been viewed as a gay icon, I assume because it (1) deals with a bunch of people with AIDS (Come on guys, we've got quilting to do!), and (2) 2/3 of the relationships are homosexual.
And there is a great deal done with the theme of love conquering barriers, of love being the same among orientations, and dealing with death and loss - in some ways I find it a cop-out that Mimi survived beyond the end of the show, though I see the reason for that...
However, in terms of the message, the central character of the story is Roger, and his journey. It's not accidental that it's made into his story (The straight - white! male), since he is presented as the fool of the group.
So let's just start with a little view on AIDS. It's a horrible disease that, once contracted, may for years be nearly impossible to detect, then will cause a slow, wasting debilitation culminating in death. We have treatments to slow onset, and treatments to slow the process, but that's the best we can do.
In other words, AIDS is an accelerated version of life. For some reason, Americans, especially, think of themselves as immortal, and as a result find fatal diseases even more horrendous. Let's face it, we're all gonna die, in many cases in a slow, wasting fashion as we gradually lose our dignity. AIDS (And cancer, and liver disease, etc, etc, etc) makes it happen sooner.
Roger is a slightly less foolish version of his girlfriend April. She learned she was going to die soon, and therefore decided she might as well die now. By that logic, we should all slit our wrists as soon as we can hold the knife.
Roger, instead, has opted to live his remaining lifetime as if he were a slowly cooling corpse. He thinks of himself as dead, and rages against the death that to him has already happened, due to his own foolishness.
The central theme of the story is the "No Day But Today" credo. It strikes a very deep chord for me. I cried when I first heard it, I cried when I heard it yesterday, and I'm tearing up right now thinking about it.
Roger is backed into wisdom. He loves Mimi in spite of himself, leaves her out of fear (with jealousy as an excuse), and at the end finally comes around to realize that he should enjoy every minute he has left.
Her miraculous revival is necessary for that process, but still bugs me in terms of storytelling. She's carried in at death's door, hears Roger's love song (That he was able to write because he's now allowing himself to feel), has her fever break in 30 seconds, and is comparatively OK.
Different things bug different people. That sequence bugs me. It doesn't help that I think of "Your Eyes" as by far the weakest song in the show. I keep thinking of Mimi reviving slightly, reaching out for Roger, then weakly saying "Roger, I love you, but you, you suck!" before falling back dead.
So, anyway, that's my take. Make of it what you will, but it's why I cry. Heavily - it was embarrassing. My damn shirt got wet.