It used to be that, in the past, there were strategic objectives that entire corporations or alliances would want to complete. Typically, money was a driver – a fountain of ISK is worth taking some risks to wrest control from your enemy (or your friend in some cases) to have it all to yourself.
Before the changes made to structures, moon mining was that driver. Such a huge amount of money would be the fund for ship replacement, which in turn encouraged your membership to want to fight, and fight viciously – so tempting that people would be willing to put huge sums of ISK on the line in terms of ships to attack or defend.
Since the removal of passive moon mining and the lack of a suitable replacement, there are no assets that are worth attacking for, or defending. Adding something worth having to the game is absolutely required for people to start squabbling, punching and shooting.
Imperium attempted to draw out the northern alliances in defence of their assets – they went on a killing spree of structures largely uncontested – they gained nothing worth keeping, and the north lost nothing of consequence.
The northern alliances didn’t risk their supercapital fleet – because rebuilding their infrastructure was negligible by comparison.