Anchorhead, have you seen THX 1138? It's even more esoteric and exposition-less than the beginning of SW. And it's been a long time since I saw American Graffiti but people praise that one as well (for different reasons, but still storytelling ones).

So I'm not sure it's accurate to say that Lucas is a poor storyteller, or that he over-explains things. I think those might be accurate for some of his more recent films*, but it wasn't always that way.

*I actually like some bits of the prequels, however disappointed I am when they diverge from the cooler story that seemed to have been hinted/planned previously.