People, organisations, leaders, politicians and militaries get complacent, because things have not changed in a long while. But things are changing and staying ahead of the curve is always hard and takes effort. The Army in Afghanistan learned the hard way not to fall into a routine, because people identify the patterns and exploit them. From my reading it's what happened to the Israel Corvette, they became complacent because they felt there was no threat. Outside of Canadian and friendly waters your ship is a big juicy propaganda target for someone.