I've been doing web application development with HTML+CSS+JS for many years, most on Unix but recently fully embedded in the .NET world. I can tell you from my experience that as good as VS and the .NET framework can be, they're way behind when it comes to web application development for cross-platform clients. (And by cross-platform I mean browsers other than IE.)
For years most of my time has been spent developing through a terminal, with Vim as my editor and the world of Gnu command-line tools as my toolset. My primary development language was a scripting language, and my code-run-test iterative cycle took seconds. Now that I'm developing on .NET, it can take 20-30 seconds to restart my application to test a change I just made, not counting getting back to the part of the app I was working on. That's using the built-in IIS server; once I deploy to a real one I've got another round of testing and coding to do because they don't work the same way.
I was much more productive in the old environment. I'm happy to see Microsoft moving towards making HTML5+JS a full-fledged member of their development system; it means that their tools are going to get much better at developing web applications, and maybe I'll be able to reach my old productivity level again.
PS: I don't get the wailing about WPF getting replaced. WPF replaced WinForms, which replaced Win32, which replaced Win16, and I'm sure I'm missing some of the intermediates. The same kind of succession has occurred in most other parts of the Windows development stack. Microsoft has a long history of deprecating APIs and replacing them with completely different and incompatible APIs. All of these WPF developers, who I assume are simply too young to remember the earlier shifts, should be grateful that the new API has a fully backward-compatible history going back to the mid 90's and can carry them forward to any platform they might need to work on in the future.
The older libraries may still be around, but they're not the recommended choice anymore and they don't support everything you can do with the newer libraries. It'll be the same with HTML5 and Windows 8: you'll need to switch to develop apps for the new UI, but old apps will still work.
For years most of my time has been spent developing through a terminal, with Vim as my editor and the world of Gnu command-line tools as my toolset. My primary development language was a scripting language, and my code-run-test iterative cycle took seconds. Now that I'm developing on .NET, it can take 20-30 seconds to restart my application to test a change I just made, not counting getting back to the part of the app I was working on. That's using the built-in IIS server; once I deploy to a real one I've got another round of testing and coding to do because they don't work the same way.
I was much more productive in the old environment. I'm happy to see Microsoft moving towards making HTML5+JS a full-fledged member of their development system; it means that their tools are going to get much better at developing web applications, and maybe I'll be able to reach my old productivity level again.
PS: I don't get the wailing about WPF getting replaced. WPF replaced WinForms, which replaced Win32, which replaced Win16, and I'm sure I'm missing some of the intermediates. The same kind of succession has occurred in most other parts of the Windows development stack. Microsoft has a long history of deprecating APIs and replacing them with completely different and incompatible APIs. All of these WPF developers, who I assume are simply too young to remember the earlier shifts, should be grateful that the new API has a fully backward-compatible history going back to the mid 90's and can carry them forward to any platform they might need to work on in the future.