You don't have to generalise with the term 'ozis'.
It can be directly traced back to the times when football (or soccer, either will do as the term soccer is basically required in this country) became known as wogball, and although this period produced some great players (and many great matches), when it began to die off during the 90s there was no real market for the sport to become broadly based along the lines of AFL and the NRL, and the Super 12s to some extent. A few 'Australian' clubs emerged during this time to set the trend of the future, of which only the Glory has been a success, as the Spirit have become regarded as a Scottish/Pommie club due to the Rangers takeover and have shifted their base away from the relative centrality of North City to Warriewood (although they still hold the record for the highest crowd figure for the regular season), Carlton suffered due to its name (Carlton the AFL club isn't that popular outside its supporter base), and Parramatta just didn't work out as planned. At the moment the Australian Soccer Association is moving forward, which is something, at least, after years of factional warfare.
Besides, soccer/football IS a very popular sport, it is just that at the Australian level it isn't a popular spectator sport, and with greater financial rewards in foreign countries (for both men and women) I doubt that a league at the level of the champions league will emerge. A highly competitive league is possible, but in a nation with such a large spatial size yet only a small population is that what we need? Perhaps we are at our best as an exporting nation?
Another possible reason is that too many people are of the opinion that the European leagues are all much better than the NSL, which may be true at times but is in no way a blanket description. Maybe if everyone were realistic with regards to what to expect from an NSL match... ?
Craig Foster does know what he is talking about, as otherwise we wouldn't be a football analyst for SBS.
Maybe he is just not interested in European matches? That would be my guess, as he is far from neutral when discussing Australian soccer/football.
edit: All of that has been taken from observations made over the past few years.