It's an interesting point. My experience with it, though, is that if the language is too simple, the complexity gets pushed off into the application. The result is "boilerplate", a lot of code that gets routinely cut&pasted into applications.
This is a frequent complaint I hear about Go: they made the language too simple in certain places. People also tend to cite Rich Hickey's distinction between "simple" and "easy".
So the question about Zig becomes one of what exactly was kept simple, and what was allowed to become complex?
I think the world would benefit from a Hyperpolyglot-style comparison here. Rosetta Code is too much of a mess; ideally, I want to see a thoughtful side by side comparison of the same program written in several languages, with commentary.