One limit of NWS is centralized control: in order to obtain data, one has to address (possibly indirectly) the nameserver, specifiying the id of the sensor.
NWS was an "all inclusive" architecture, more a proof of concept than a real application. It was not applicable to a grid scale, mostly for the absence of a real database.
The distributed nature of the LDAP architecture is appealing from this point of view: information is organized hierarchically, and the resulting tree (might be) distributed over different servers.
In a Grid perspective, the hierarchy often reflects the organization of the Grid: the first level under the root is composed of continental networks, below are national networks and next local networks. Leaves are single resources, like clusters of computers, single computers or storage elements.