I suspect the reason that this hasn't happen is because HTML has always been an evolving standard. So while you can use your copy of Quark from ten years ago today, you wouldn't be advised to do that with a ten year old copy of Dreamweaver if you want to make an HTML5 site.
Another reason Photoshop comps exist is because of clients who can't comprehend the abstract. As someone who does IA I can tell you that time I've had many clients (who are very intelligent) who just can't go from the abstraction of quickly done wireframes that show navigation to what the final site will be. So until you have clients like that (and maybe they're a generation away) you'll need Photoshop to what that final site will look like. And I say that knowing that Photoshop is really a hack given what the sites can do.