This is a link to the earlier thread on impf. vs. aor.
http://discourse.textkit.com/t/odyssey-book-ii-use-of-imperfect/11269/1
The comments by mwh towards the end are particularly insightful.
I think there are similar questions as to the choice of active vs. middle vs. passive. Metrical convenience sometimes must play a role in these choices. Also, I suspect certain verbs have a preference for one voice or another, regardless of semantics.