On the topic of object browsers, I'd argue that "no significant innovation" has been made at the intersection of object browsers and Web browsers since around 2001 when Joe Hewitt checked in the original DOM Inspector for Netscape, aside from possibly the inline display of the results of expressions evaluated in the console. (DOM Inspector didn't have such a console.)
In many ways, browser devtools are worse than the DOM Inspector that was baked into Firefox 1.0. The node tree was fast, and you could open up not just a view for more than one object, but more than one view of a single object, too. Meanwhile, in the tools baked into major browsers, I can't even look at the "Layout" pane and the CSS "Rules" pane at the same time. Want to have the document's DOM tree on the screen while looking at some JSON returned by an AJAX call? Too bad.