There's lot of truth on the post by @ppk "Stop pushing the web forward", and it has lots of replies, some very insightful and others that don't follow the reasoning. This is my take on it and you can bet that it will be closer to the clueless ones.
Browsers are adding new features, are constantly trying to find out what's missing and fill those gaps. That's great! we don't really want a whole full stop because we're always wishing than something works better, it's faster, it's doable...
But the current problem is that there are just too many new experiments, while old problems remain ignored and unfixed. You find a post stating that something is coming to the alpha version of a browser, that they plan to work on new features for the next release, but we're not able to correctly use the previously released features because it fails in some situations or it's implemented only in one browser and so it can't be used on the public web.
We need that those gaps are solved, we need to be sure that the existing problems are fixed before even more features are added.
For example pasting images into web pages:
Firefox pastes the data as base64, but it won't work on an input. But if you save it as a file in your computer, then you can Copy&Paste it and no other browser allows that.
IE11 won't paste any image unless you're using a contentEditable element, and in that case it even embeds the images included in a MS Word document, this isn't possible in any other browser.
Chrome allows nicely to paste a screenshot into an input, as explained above the other browsers don't allow this.
So a "basic" feature that users would enjoy across so many sites but that it isn't available in full form in all the browsers, don't you think that this is a good example of something that should be fixed before adding something absolutely new?
We'll always need better developer tools, tools that allow us to look at the pages and get more information, options to show warnings when something is wrong or we are using deprecated APIs. Don't get me wrong, the current tools are a million times better than what we had a few years ago but they still can be better: I'm in love with the CSS changes pane in IE11, there's no match for the mobile options in Chrome, I enjoy the UI from Firebug. And surely you can tell many things that you miss and wished that they worked better. All of this without new APIs.
So taking the time to review the bug trackers and clean them up doesn't mean that the web stops, it means that we remove the problems that we have and we can have a better solid future instead of lots of APIs that we can't rely on due to the number of bugs.