If you go to youtube you can find Vice-Presidential candidates all the way back to Ferraro giving concession speeches, although not from the same location as the Pres.
Moreover, the purpose of the concession speech is not just to say I lost and accept the results of the people. It is also to thank the people who fought for you.
In the 2000 and 2004 elections the losers were sore losers and did not make proper "concessions" as we know them.