The real reason for the use of the iterative form is probably that it fit in a metrical slot where the simple form would not fit. I think you really have to strain to see a difference between 59 and 272. But meter is ultimately bound up with the formulaic aspect of the Homeric poems: the verbs are generally speaking embedded in formulas which have specific metrical characteristics. The aoidos generally composes not be selecting specific words, not by deciding whether to use the simple or the iterative form, but rather by choosing a specific group of words constituing a formula. He has two ways of essentially saying the same thing, depending on what he needs to say in the rest of the hexameter. He joins two formulas with specific metrical properties together to make single hexameter verse.
By the way, since you’re struggling with the aspectual difference between imperfect and aorist, you should go back and read this thread in its entirety:
http://discourse.textkit.com/t/odyssey-book-ii-use-of-imperfect/11269/1
Pay particular attention to mwh’s comments towards the end. He knows Greek better than any of us, and I think his process/event distinction makes the most sense for understanding Greek aspect. As he notes, there is a semantic difference between the two aspects–process vs. event–even though the aoidos’ choice may be constrained or at least guided to a greater or lesser extent by the exigencies of the verse.