There is an obvious inequality between the number of card abilities modifying Attack Dice and the number of card abilities modifying defense dice. This inequality is necessary to a degree: the game should favor offense to keep it exciting for players. A combat game in which none of the components can blow anything up is horribly boring. Too much modification for Defense Dice is just as bad as not enough modification for attack dice. Even with three fully modified attack dice, it is difficult to hit a 3 AGI ship with a focus and an evade (I'm looking at you, X7 Defenders.) With two attack dice, a tokened up 3 AGI ship is nearly impossible to hit.
So game content must favor offense over defense, but how much is too much? The game stops being fun when every attack hits. So is Fenn Rau too much? Not really, Fenn Rau is one pilot who takes up a third of a 100 point list, and he is far from invulnerable. Added to all the other powerful offensive options in the game, Fenn Rau contributes to the perceived shortage of powerful defensive options. There number of defensive upgrades and pilot abilities is increasing, but they are not as obvious or popular. Take Sensor Cluster for example: on a T70 it might be a life saving defensive choice, but most players will spend their points on offense, because the better offense usually wins. I'd like to keep it that way.