I think that Morrison's intent is right. As others have stated, many authors have tried to reconcile the bondage with the positive, feminist stance of Diana. The fact that they continue to do so shows that it's not sticking, or at least not in an ICONIC manner. I consider myself a relatively enlightened adult regarding feminism and it took bluefall's "When Wondy was Awesome" to finally make me think that perhaps there WAS something to be found in Diana.
There are several factors that I think keep Diana from really being an icon. And I don't think she's an icon at the moment. She might be a cultural one - when people are asked what superheroines there are, obviously Wonder Woman comes up there, and Linda Carter, and you'll have any number of starlets saying that Wonder Woman is an empowering heroine and that's why they'll dress up as her at Halloween - but she lacks the oomph of Batman and Superman. When people talk about Superman, it isn't as an empowering icon to the Jews, or any of that. He's Superman. Similarly, Batman may be mocked by fans and casual observers for his backstory ( kid can't get over his dead parents, waah waah) but as the Bale movies have shown, people still feel strongly about the ultimate self-made superhero.
Without further adieu...
1. Origin story It's too damn convoluted. So, she's a girl, and a USAF pilot is shot down, and she helps close the demongate, and that's where they get the American flag on her butt...but wait, there's Steve Trevor, and the Amazons are...defending the gate, no, they're hiding, I'm sorry, what? Make it simple, make it resonate. That's why Superman and Batman work, it's why Spider-man works. Last survivor of a dead race. Saw his parents shot in front of his eyes as a child. One selfish moment allows a man to kill his uncle. People will tinker around the edges with all of the above but they don't change anything fundamentally. Diana's needs to be simplified and make it resonate emotionally.
2. Role/Mission Make it clear what she's out here to do. And, importantly, LET HER DO IT. The one that I grew up with is the idea that she was a diplomat to Man's World, and it's the one that works best, so let's keep it, eh? Though I would remove the Man's World caveat. Don't make this a gender conflict, because Diana should rise above such pettiness and it goes into some troubling issues that a comic book hero should try to avoid in a play for iconic status. She's there to show the world another way out. It works especially in the Trinity - if you have Superman as Defender, Batman as Avenger, and Diana as Healer. While I admit that it's a bit of a stereotype to put the woman in that role, it's the one that she's been doing all her publication history, so don't change anything there. The alternative is Warrior, but then you have the warrior-chick stereotype, which while awesome in its place is not quite the ethos one should expound as a Superhero. That is why I like Cooke's Diana in New Frontier - she's not afraid to get her hands dirty but overall her purpose is one of peace and reconciliation.
3. The Amazons This is the trickiest one, I feel. I remember bluefall positing that Amazons were Humanity 2.0, and that seems to be the intent of Marston. But there just is far too many problems with this view. One, that means the Amazons are superior to us. Not just physically, but morally, ethically. I don't think many people are okay with the idea of a Superior Race. Two, it gives something for writers to tear down. Writers are all about that. Krypton has undergone this. The Guardians have especially suffered from this. And the Amazons have been utterly destroyed by this several times over, to the point where you wonder how can there BE any Amazons. Find another way around this. Maybe they are there to help guide Man's World to Humanity 2.0? Have them represent emotional and religious zen? I don't know. Three, gender war.
These are the three key things I think need to be addressed to make Wondy a true icon in her own right, with no caveats attached.