Sorry, I really don't see your point.
Here's how I see it....If it's not broken, don't fix it.
The Aussie Open has been doing well for ages, so I really don't see the problem with it's location.
People aren't there for the bars, beaches, and landmarks...they are there to watch tennis. The same goes for players, as rexman said.
And who cares if foreigners think Sydney is the capital? It wouldn't make the tournament any more appealing than it already is. I really could not care less about where a Grand Slam (or any tournament, for that matter) is located...big city, small city, middle of nowhere. Do you really think people wouldn't come if the US Open was held in Sand Springs, Oklahoma instead of New York City? The place would still be packed. People go for the tennis, not for the sights...which is why most of their time is spent in the stands and on the grounds, not strolling through the city. In my opinion, it's just an added bonus...but definitely not a necessity.