Well, like most other sports and aspects in a culture, trends in
society influence rules and social trands in Aussie footy as
well.
Since safety measures have been introduced for possible AIDS
spread, likewise, the AFL introduced 'the blood rule' some years
back, where once a player's skin is opened, he is to leave the
field.
Even the style and nature of the game have been influenced by
trends of other growing sports within Australia - such as
basketball and rugby: coaches decided to introduce a playing
philosophy of 'team possession' over the previous playing trend of
"territorial football" as previously played.
Even the watering and upkeep of the grounds are influenced by
current societal trends and concerns.
But trends influence all aspects of any sport; these are just a
couple re Aussie Rules.