What's the alternative? OS/2 had nice features; it got crushed. BeOS had some nice features; it got crushed. (Yes, I'm aware that they're probably still around in some OSS version.) Plan9 keeps being mentioned, but do regular users understand it? (Is there a "this is why we do things, and this is why that's good" written for people who haven't written their own compiler?)
Are people working on experimental new OSs to "fix problems" in existing systems, or have we gone way past the point of no return? Is there any work on new microprocessor architecture? How much stuff in my modern OS is there because of legacy 8086 stuff?
I think, but I'm not sure, that the length of time it's taken people to get (for one example) IPv6 rolled out shows that change is not likely.
Plan9 LiveCD and installer: (http://cm.bell-labs.com/plan9/download.html)
Haiku: (http://haiku-os.org/)