This is one of those things where you have to imagine events from the perspective of the character, and not the guy writing the movies. And when you do that, it makes a lot of sense.
Yesterday, wondering the kind of things you're prone to wonder about in the workday wasteland that is early January, TheCrazyMonk asked if Obi-Wan would ever have confronted Luke about his "destiny" if Leia and the Alliance hadn't crashed on his front doorstep and a couple of droids ended up in the hands of a kid.
"I don't think Obi-Wan ever meant to confront Luke", they write. "I subscribe to the notion that the whole thing was an elaborate trap to lure Darth Vader there for a final battle to the death."
"He takes Luke there as a child, doesn't even change his last name to anything other than Skywalker, and leaves him with Vader's mom's family on a sparsly [sic] populated planet so there's no over abundance of life to hide the kids force talent which is sure to manifest. Then he just sits there in the desert, waiting for Vader to show up so they can throw down."
It's a convincing argument! It goes off the rails a little bit with some of it's grander ponderings (like Luke becoming some kind of "guided missile"), but its premise of Obi-Wan setting an obvious, patient trap is a cool one.
Of course, it all goes wrong for Obi-Wan since it takes decades for Vader to show, but hey, as the blue ghosts show at the conclusion of Return of the Jedi, he got what he was after in the end.