Unless you plan on moving away from Louisiana, there's no reason not to get it done there.
One caveat, however: Few, if any, lawyers in Louisiana will be knowledgeable about probate and estate laws in Australia or any Australian state. It might be advisable for your will to contain specific provisions or language to deal with your assets in Australia. For that reason, you probably would want to have an Australian lawyer either work with your lawyer in Louisiana and/or review whatever your Louisiana lawyer prepares.
Out of curiosity, what sorts of assets do you own in Australia, and why do you continue to own them despite having been in Louisiana for however long you've been there?