There's a few points here:
1) Not all data is text. In fact, very little of the data people see/work with day-to-day is raw text. It's silly to transform a PNG image into text to be able to pipe it around. (Or to pipe around its filename instead and have a dozen tools all having to open and re-parse it each time.)
2) There's nothing on PowerShell preventing you from serializing a piece of data to text if you want to. The key is: you don't have to.
3) Systems that depend on 50,000 CLI tools all having their own ad-hoc text parsers are cemented, mummified, cannot change. You can't change the output format of ps (to use an example in this thread) without breaking an unknown number of CLI tools. Even if you come up with a great way to improve the output, doesn't matter, you've still broken everything. This is less (but not none!) of an issue with PowerShell. I like computers to evolve to become better over time, and text-based CLIs are a huge anchor preventing that.
If you’ll wrap your objects into some platform-agnostic protocol like JSON, you gonna waste enormous amount of CPU time parsing/formatting those streams at the object’s boundaries.
I tend to dump out data structures to line terminated JSON, and it works out really well for streams, can even gz almost transparently. Parse/stringify has never been the bottleneck... it's usually memory (to hold all the objects being processed, unless you block/pushback on the stream), or IO (the feed/source of said stream can't keep up).
If you expose JSON, each serialize/deserialize will produce another instances of objects, with the same data.
The architecture of PowerShell implies commands in the pipeline can process the same instances, without duplicating them.
Another good thing about passing raw objects instead of JSON — live objects can contain stuff expensive or impossible to serialize. Like an OS handle to an open file. Sure, with JSON you can pass file names instead, but this means commands in your pipeline need to open/close those files. Not only this is slower (opening a file requires kernel call, which in turn does various security checks for user’s group membership and file system’s inherited permissions), but can even cause sharing violations errors when two commands in the pipeline try accessing the same file.
PowerShell works over networks just fine, because standardized ISO/IEC 17963:2013 protocol a.k.a. WS-Management.
You phrase this as if changing things for the sake of changing was a good thing. It is not.
Well, perhaps it is good for the software vendor, but from the customer's point of view, having to re-learn how to do the same stuff over and over every other year is a PITA.
Without change, there's no improvement.
Secondly, if you used DSV to parse PS, like you should, adding a new column to the end won't break anything. A fancier parser won't even break if you add to the middle, but that's usually not worth the effort to write.
Text can be poorly parsed by everyone, yes. I especially love it when the default tools settings mean two different computers will give different text results, because the installation defaults changed at some point. What's not to love about trying to properly escape and unescape strings via the command line, while simultaneously keeping in mind your own shell's escaping, and having scripts which are neither backwards nor forwards compatible? And this is to say nothing of different distros.
It's as if the text was built for humans instead of my tools half the time, or something. I usually try to centralize my parsing of text in one place so when it invariably breaks, I don't have to rewrite my entire shell script.
Some basic structuring - I hesitate to call it a brittle object model, when most of the time I'm dealing with something more akin to C structs than invariant and abstraction laden Smalltalk or somesuch, or Java's sprawl of factories and inheritance - makes things a bit easier. New fields can be added without breaking my regular expressions. I don't need to worry about escapes to handle special characters. I can trivially dump to text for display (by simply running the command as this is the default behavior of the shell), or to feed into text consuming tools.
Now of course you can always format to text from your structured object, but this does not matter. What matters is what is convenient in the proposed UI, and what is mainly practiced in the real world because of such convenience and the amplification loop it creates between tools authors and users.
Also some objects are originally handled in text form, and their structured decomposition is extremely complex compared to an informal description and the naturally refinable heuristic which comes with it. For example you can grep into a source code in any language (with more or less efficiency depending on the language, but at least if there is a unique symbol you will find it), whereas trying to get and handle it in a structured way basically means you would need half of a (modular) compiler, and a huge manual to describe the structure, and possibly a non trivial amount of code to actually do the lookup.
The PowerShell approach is not all-bad, though, and obviously there are some usages where it superior to text based shells. But for a day to day usage as a general purpose shell, and a programmer shell, I'll stick to the Unix approach.
If code was stored in a structured representation you could still search for a string object containing a symbol name in the structured representation. You can match a structure pattern just like you match a regex to text.
Typical shells can be thought of as REPL for a programming language that makes the file system easily accessible and uses said file system or pipes to pass around data between functions/commands, sometimes as human-readable text. Most programming languages don't encourage passing data around as strings.