Languages should make it easy to use third party pieces directly, without a package manager. People actually do that, and so that status quo is maintained; any increment in the difficulty of constructing programs out of components will result in loud protests.
Package managers are an anti-pattern. When the standard package manager is present, the packaging problem is regarded as solved ("just use the package manager"), and so the actual mechanisms underlying program construction are then out of the negative feedback loop and will rot.
Imagine a world where your language’s package manager became a company that basically offered “Package Management as a Service”. How effective do you imagine that would be?
