Those teams are far from lightweight, especially after long qualifying programmes. Oceania was in the recent past a minor confederation, however when FIFA granted it full status it required a direct entry spot as otherwise there is no point in it existing as a separate entity. Also, FIFA cannot just do whatever it likes if it makes a point of promoting the game in 'developing' regions yet fails to treat Oceania with the respect it deserves.
It is far from a free ride for Australia, too. We aren't the only 'power' in this confederation.
My point regarding Asia has nothing to do with easier games, but more games, as ... pointed out. Through a proper qualification programme our team will be prepared, rather than the current garbage that we forced to deal with. In that way we could also deal with failure to reach the World Cup, rather then be caught up with a single defeat that ruined our chances of qualification.
edit: I can see the point that you are trying to make. It's a bit of a bastard that political factions dictate the agenda of what is meant to be the governing body of the world's greatest game. But that's the reality, so all that I can really do is complain.
I'd prefer to see Oceania play through Asia, too, rather than it be given a single spot as a separate confederation. However, if we were to get that spot it would be a great bargaining piece to use in any negotiations regarding the inclusion of Oceania into Asia...