Powershell accomplishes this by making the pipes pass tagged objects around containing streams. This actually has a lot of nice properties when you go to manipulate the objects programatically.
And it's a logical extension of the UNIX stream model, where in reality you're passing around a whole heck of a lot more than text when you type 'cat | sed'. You're passing environment context, multiple streams, etc.
The idea that this is "more complex" than unix pipes is understandable, but the reality is that IPC is pretty complex and a whole lot of magic and shared expectations go into the "simplicity" that bash offers. And even then that model breaks down all the time (e.g., as Docker becomes common as a deploy target the idea that you should output error conditions to STDERR has rapidly become problematic).
