So if someone asks about angle of attack during a bank do you think it's sensible to assume, given that he's not mentioned slipping or skidding, that we are talking about a steady state, balanced turn.
But the OP did not ask about bank angle. He/she asked
why the dihedral design causes the the lower wing to have a larger angle of attack than the higher one during a bank?
He/she was clearly attempting to discuss the situation in which the dihedral design causes the lower wing to have a larger angle of attack than the higher one.
Instead of answering this question, you decided to add further conditions.
What question do you think the op was asking?
The majority of the posters in this thread appear to have had no difficulty in interpreting the question in the manner intended by the OP. Only you appear to have applied a different interpretation. In doing this you have made the question irrelevant.
Who does that suggest has got the wrong interpretation?