because you probably don't know what to look at after all. Look at the predicated type declarations for example. It's a language with concepts built in.
I did not in fact read all 63 pages (!) of the language reference, but as for the predicated type declarations (found here[1], for the curious), I agree, they are very cool.
Let me clarify: I'm not saying the language does not have good parts to it. I'm not even saying that there's no room for a new systems language. I'm just saying for my use case, I can't justify using it and I'll stick with Go for now.
[1] https://github.com/jckarter/clay/blob/v0.1.0/doc/language-re...