Then why are 'Linux' and 'Clang' in the good pile?
Linux is just a totally made up name, that's only mildly similar to 'unix' (which even fewer people likely know these days). Nobody's going to be able to guess what Linux is just by the name.
Clang is DEFINITELY not obvious at all. I only JUST NOW realized that 'Clang' could be read as a combination of 'C' and 'lang' (and I've used it as a compiler/analyzer a fair bit!). Maybe the people that run the project pronounce it as 'c-lang', but I doubt most people would read it that way.
On the other hand, most people would likely guess that Phonon has /something/ to do with audio, even if they aren't familiar with the word 'Phonon' itself. People might not guess that 'Amarok' is a music player, but the 'rok' at the end of the name is something they'd likely be able to use to help them remember what it is.
(Personally, I also don't like the name 'Libre Office' either, simply because saying it feels like the vocal equivalent of banging the keyboard randomly)
As sorpigal (and others) have said, I'd disagree that a name must instantly say what the software's function is. It can work, as long as you're consistent with the pattern (Apple having done a fairly good job with i<Word>, although they also have <Word>