One can see from the code on the WordPress Importer Plugin that it was a thought decision to bail early when imported posts had
post_date matching existing posts.
For that reason, they don't run the imported versions through
wp_insert_post() which would update them accordingly. There are also no hooks to modify this behavior.
Does anyone know a of a clear reason for this? Was it just a decision-not-options design or are there's any hidden gotchas that could creep from that sort of repurposing?
I'm trying to decide wheter I'll send in a patch adding that hook or actually fork this and build my own version without that restriction, so it would be handy to know.