curl command lines can get huge and unwieldy. If a curl command has a huge amount of input, that gets unwieldy, too. Same thing with data input.
The fact that your requests persist and can be repeated and modified is useful. Better than looking up past commands in ~/.bash_history.
I, on the other hand, can take quite a while to type out a cURL request with 4 custom headers and a long JSON body.
While I spent most of my day at the CLI I do step out for a few choice applications. Being able to quickly save and compile a bunch of requests to replay is also nice though I'm sure you could do that with cURL or similar tools.
It doesn't hurt that the app is particularly nice looking either :-)
This just might be, and it'll write the curl command for you too :)
https://metacpan.org/release/App-RecordStream
https://metacpan.org/pod/App::RecordStream::Manual::Story
https://metacpan.org/pod/App::RecordStream::Manual::Examples