Defending yourself actively is a good part of the game. Yes, the game is based around % chance based on your statistics, but you get abilities that can change these numbers drastically for the short time to change the dynamics of a fight. There are stuns, mezz's, knockdowns, roots/snares that will stop an enemy from attacking for a time, slow them down/root them in place so they cannot run away/kite you, or close distance with you. There are enemies that will make it necessary to use your interrupt ability, to stop large damage attacks on your party, or yourself.
I think once you get into 15+ group content, or at the very least level further into your story content, you will see more things that demand more from you then 1-2-3.