I'm not a huge fan of cURL, but most people who use cURL don't use the command line either. They use the cURL library and access that functionality through a high level language (PHP, C, C++, whatever).
Here's some sample curl client code in PHP.
$c = curl_init("https://someurl/some/api");
$msg = /* some data here */
$opts = array(
CURLOPT_POST=>TRUE,
CURLOPT_USERPWD=>"<password string>",
CURLOPT_HTTPHEADER=>array("Content-type: application/json"),
CURLOPT_POSTFIELDS=>$msg,
CURLOPT_SSL_VERIFYPEER=>FALSE,
CURLOPT_RETURNTRANSFER=>TRUE
);
curl_setopt_array($c, $opts);
$d = curl_exec($c);
curl_close($c);
I completely agree on cURL's design though. It's painfully obvious when working with the cURL bindings in PHP that it didn't have much thought put in to adapting it to PHP's constraints and is essentially just the command line client in a "nice" wrapper. It ends up being a huge pain to work with.