Sorry if I just put it out there, but I think the "I am your father" works just fine within the confines of the film.
You get things that seemingly don't make sense (like that Yoda and Ben-ghost don't tell him before his departure), but then, Luke doesn't get it as well and constantly lampshades this fact himself after that scene.
He's hanging there alone and helpless, and Benghost doesn't help him despite earlier appearing to him in an earlier moment of physical desperation, and casually helping him out with the Death Star (one of the cheesiest moments of that film).
We get some sensation that it's because Luke transgressed his boundaries and now has to face the consequences alone, or maybe that Ben "can't" help him at the moment because something forbids him from doing that, so Luke can go through the "test" alone... whatever. It all leaves us as shocked and desperate as the protagonist himself, and then the movie just ends and we're left with a dark, depressed feeling and utter confusion - again, just like the main character.
It's only then, when ROTJ comes along, introduces the final nail in the coffin of universe-shrinking retcon, and fails to justify the stubborn silence from the last movie despite at least two infodump dialogues, that the "flaw" is seen for what it ultimately is.
Which only makes one wish they'd put more effort into that last one.