It just makes sense and also optional, so whoever doesn't like it can go back to using parentheses.
Syntax similar to default, without use statement and short for "return".
function($item) use ($baz) { $this->foo($item + $baz); return $this->bar($item); }
to
fn($item) { $this->foo($item + $baz); => $this->bar($item); }
It's like Accessors/Mutators in Laravel but native.
For me, the most important argument is that the pipeline pattern is a tried and tested pattern, that this RFC builds upon. A couple of examples:
This RFC adds syntax to make using these kinds of pattern much more convenient.
On top of that, there's the argument that multiple modern languages support a pipe operator:
Finally, I've had numerous occasions where a pipe operator would simplify my own code — I have more than a handful real life cases where this would be useful.