I feel certain that at least two of these are crowning successes.
I have the most first-hand experience with CML2. One weekend I used it to hack together a project I called Compache. It used the CML2 GUI to configure all the settings, modules, and patches desired for a particular Apache build, then built it. (anyone remember how painful compiling a full-featured Apache 1.3 could be back in the day? Some of the worst dependency hell I've ever experienced)
In concept it worked great. The GUI was pretty and the dependencies were decent (it did require a few gross hacks, I forget why). In practice it was horrid, mostly due to CML2 limitations. Initially I had good correspondence with ESR and tried to help finish some important features but with each release it got slower, crankier, and the finish line felt further away.
In my experience Reiser3 was a failure too: it was merged before it was ready, Hans moved on to other stuff, and it took years for others to stabilize it. Since Resier4 was going to be a significantly MORE intrusive patchset, I think the kernel team was prudent not to make that mistake again. Disclosure: I suffered data loss due to a well known and long lived Reiser3 bug so I'm not the most impartial party here.
So, I see CML2 and Reiser4 as a perfect example of how the kernel process keeps questionable ideas on the sidelines until they've been shaken out. Shame about all the Aunt Tillie vitriol on LKML of course.
I don't see much need for FatELF on any of my systems, but I definitely do see a need for a better scheduler! Wish I knew more about the CFS story.