i don't think another "i am your father" moment will ever work again for star wars, simply because it's too well known for it. i think it's more like just a plot point that they saved for VIII, partially because we don't need to know everything in this movie to enjoy it (think of how in IV there was no hint that these main characters-- luke, leia, vader-- might even have a connection) and partially just to give these characters somewhere to go for the next chapter. rey being a skywalker won't be a surprise because by then, after we've all seen it 120 times on blu-ray, we'll have figured it out. it'll be more like the kylo ren reveal, just something that's said through the course of events, and now where are we gonna go with it.

it matters that rey is luke's daughter because people are getting mad at TFA, thinking it's "the force discovered," when it is indeed-- as the title suggests-- the force being awakened in her. she's already strong with the force, she's already been trained enough to take down ren, and based on her lineage she has a path to becoming the most powerful jedi (or sith) in the galaxy. she just happens to have no idea about any of it when we meet her. she thinks she's a nobody orphan from planet nowhere (and despite all the clues, lots of people are walking out of TFA thinking the same). as a setup, it's kinda brilliant.