Programatically access field settings

I was looking for a way to get field settings programatically.

Here is my code:

/* @var $field_item \Drupal\Core\Field\FieldItemBase */

// The line below causes fatal error "Call to protected method".
// $allowed_values = $field_item->getSetting('allowed_values'); 

// Workaround.
$allowed_values = $field_item->getFieldDefinition()->getSetting('allowed_values');

Are there any reasons to keep FieldItemBase::getSetting protected?