I think you're arguing both sides of the argument -- numpy arrays do have a lot of similar, related operations (because numpy uses them internally -- since they're more efficient) which means they're not fringe.
I'm advocating that the built-in list class add the efficient, convenience methods -- especially since it wouldn't be overriding other methods, it would be leveraging standard methods that are currently unimplemented -- https://mail.python.org/mailman/listinfo/python-list
