Although it seems logical, at least at first blush, to give a class defence bonus to the class's atypical strength, mechanically it's a seriously poor idea given that the class's strength is already represented by a primary stat.
I'm sure I'm not the first to think of this, but given the gamist nature of 4e, isn't it more logical to give the defence bonus of a class to the class's WEAKEST defence?
I'm sure I'm not the first to think of this, but given the gamist nature of 4e, isn't it more logical to give the defence bonus of a class to the class's WEAKEST defence?