Why would that be better than using a keyboard to navigate between discrete units on the screen? There are a set number of clickable points on the screen, why make a game for the blind user to try to echo-locate those spots instead of just letting them cycle through them? The point of a screen for a sighted user is to make a concise way to transmit existing information... it is only a good way if you are sighted.
how do you echolocate a shape? It seems you are suggesting some mapping of a 2D visual scene to audio. If that is useful in practice, it is one of many possible interfaces that blind people could use. It wouldn't supplant screen readers.
