Unix-like pipes are not restricted to sending text, they may send general bytestreams. Modern data serialization formats (flatbuffers, capnproto, msgpack, etc.) are highly efficient, and using serialization makes it easier to deploy applications in a distributed setting.
The value is in having everything speak a common standard. In unix, that 'standard' is lines of text, which is inherently linear and lacks the ability to idiomatically represent hierarchy.
Conceivably, one could use modern serialization formats or we could do something a bit more interesting, like supporting some notion of "objects" directly in the operating system or runtime (in the case of powershell, the "runtime" is the .net vm; in unix it's the OS).
Such text can be parsed by both human and computer, because computer can just jump from field to field without parsing everything in between, like humans do.
Sure, but the standard GNU or BSD userland doesn't do that, does it? If you're going to the trouble of implementing your own userspace, then you might as well use a consistent, proper data serialization format (either text or binary, but text is more accessible).
