Keep in your mind few things:
1. This topic was openned because someone asked about how improve the defense skills. If he need more def , EA is one of answers avaliable;
2. When the pools was designed incarnates was no avaliable and fitness was optnional not inherent;
3. E.A. importance depends of combination of pools , Archetype and figth strategy. It also works as good taunt and damage skill; you can slot procs like damage, heals, endurance and desorient there