Discontinuation
While Nintendo hasn't come forward explaining the reason for the discontinuation of the device, manufacturers Buffalo Technology are reportedly no longer licensed to distribute it due to a successful recent lawsuit by the Australian Government's technology research agency CSIRO (Commonwealth Scientific and Industrial Research Organisation). As a result, the company has been prevented from trading in any products adhering to the 802.11a/g standards in the US, including the Nintendo Wi-Fi USB connector.
Nintendo, however, only states on their website that the device is discontinued and says that a standard wireless router should work with the Wii. Here is their official statement:
"Please note: The Nintendo Wi-Fi USB Connector has been discontinued until further notice. As an alternative for on-line access, Wii owners can use a standard wireless router, or the Wii LAN Adapter."
Read more about this topic: Nintendo Wi-Fi USB Connector