Why the Tempest?

 I'm reading Margaret Atwood's Hag-Seed, her retelling of Shakespeare's The Tempest. I'm mystified by great writers' fascination with this play. Neil Gaiman wrote a whole episode about it in his Sandman saga. These are two of my favorite authors. I've read the Tempest twice, once in college and once after, in an attempt to figure out what I'm missing. I haven't.

After a made-for-Hollywood opening shipwreck, Shakespeare segues into what must be the number one entry in 101 Ways to Kill Dramatic Tension, i.e., an extended monologue describing all the backstory the audience needs to know to understand the story. In any contemporary story, it would be a neon sign blaring "amateur writer here," and no editor would bother reading past the first page.

For those still awake when Prospero is done, we have learned that we are watching a simple revenge story, which is a lame and suspect plot device. We can generate some sympathy for the usurped Duke of Milan, but not a lot. After all, he's only the "rightful Duke" by luck of birth. He remains a morally gray character, enslaving the indigenous inhabitant of the island, Caliban, and an air spirit. His devotion to his daughter borders on the controlling and creepy.

The remainder of the play is a collection of wandering happenings, bringing people into their proper places so that Miranda can be married to the heir of Naples, and the usurpers punished. Missing is any dramatic tension. We wonder what is happening, and maybe how it will all happen, but never do we worry that it won't.

After all has been satisfactorily handled, Prospero makes another speech, in which he vows to give up sorcery. It's as if Shakespeare knows that magic is morally suspect, and wants to clear his hero so he can be triumphantly virtuous. If so, it's a thin apology, analogous to a bank robber sitting on $50 million, and declaring he's giving up crime. Good for you.

But many great writers and lovers of literature love this play. What am I missing?