How to overwrite a specific parameter in a core taxonomy?

The Codex page for register_taxonomy says that

This function adds or overwrites a taxonomy.

How can I use it to overwrite a core taxonomy without redefining all the parameters ?

For example, let’s imagine that I want to make the core posts categories read-only for everybody. I can achieve that by setting the edit_terms capability for this taxonomy to do_not_allow.

My first guest was to call the register_taxonomy with only the parameter I want to change :

add_action( 'init', 'u16975_disable_category_creation' );
function u16975_disable_category_creation(){
    register_taxonomy( 'category', 'post', array(
        'capabilities' => array(
            'edit_terms' => 'do_not_allow',
        ),
    ) );
}

But this does not work as it also overwrites all other parameters and set them to the default value (ex: hierarchical is set back to false).

The only way I found to achieve this is to use the global variable that stores all registered taxonomies.

add_action( 'init', 'u16975_use_global_var' );
function u16975_use_global_var(){
    global $wp_taxonomies;
    $wp_taxonomies['category']->cap->edit_terms="do_not_allow";
}

Version 4.4 saw the introduction of the register_taxonomy_args filter in register_taxonomy() which you can use to filter the arguments used to register a taxonomy

/**
 * Filter the arguments for registering a taxonomy.
 *
 * @since 4.4.0
 *
 * @param array  $args        Array of arguments for registering a taxonomy.
 * @param array  $object_type Array of names of object types for the taxonomy.
 * @param string $taxonomy    Taxonomy key.
 */
$args = apply_filters( 'register_taxonomy_args', $args, $taxonomy, (array) $object_type );

So you can do the following:

add_filter( 'register_taxonomy_args', function ( $args, $taxonomy, $object_type )
{
    // Only target the built-in taxonomy 'category'
    if ( 'category' !== $taxonomy )
        return $args;

    // Set our capability 'edit_terms' to our value
    $args["capabilities"]["edit_terms"] = 'do_not_allow';

    return $args;
}, 10, 3);

On all older versions, you would either need to re-register the complete ‘category’ taxonomy or use the way you have done it in your question

EDIT

The Codex page for register_taxonomy says that

• This function adds or overwrites a taxonomy.

That is exactly what it does, it either creates a custom taxonomy or completely overrides and register a core taxonomy, it does not add any extra arguments to the existing taxonomy