User blog comment:CatalinMetro/Nintendo Wi-Fi Connection is closed!/@comment-6019507-20140602101435/@comment-5254117-20140602230024

Because according to them, the Wii and DS are outdated systems, and "nobody uses them anymore." Anyone who does use them will now have incentive to buy a 3DS/Wii U, and Nintendo doesn't have to pay for services on "outdated" consoles.