The HTTP Request is the barebones of most Nodes. A way to use a POST or GET to communicate with a 3rd party API.
What I would find useful is configure an HTTP Request and then save it as a Custom Node. At that point the configuration and options would know longer be changeable (in fact it would no longer look like an HTTP REquest Node). Although there would be an option to convert an instance of the Custom Node into a configurable HTTP Request Node if future modifications were needed.
In a sense this is more like a template feature than a pure custom node.