I'll agree that the web is significantly better than it has been in the past, but it's still not ready to drop the plugins quite yet.
I'm currently working on a "web application" that has a minimum requirement of IE9, FF4, Chrome10, etc. You'd think that this would give me the latest the web has to offer without headaches, right? No.
None of the browsers can agree on how to render fonts specified via @font-face (oddly enough, IE9 is the only one to get it right), the supported a/v codecs vary from browser to browser, and each browser has its own selection of the HTML5 spec implemented, so sometimes I have features available and other times I'm boned.
Ultimately, this has forced me back to using a Flash plugin for audio support, simply because I don't feel like storing multiple copies of every sound file (or having to do other tricks to generate something each browser likes), for the fonts I'm still stuck using server side junk to generate images, and I don't even know what headaches I will have to deal with when it comes time to deal with the canvas stuff and other video-related features.
Do I like it? Not at all, but my hands are rather tied. I can either suck it up and use commonly found and accepted plugins to solve my issues or I can spend (potentially) boatloads of time looking into ways to deal with individual browser quirks and/or missing functionality.
The whole web-as-a-platform thing has indeed come a long way, but I don't think we're ready for a plugin-free web experience yet.