I approve of your username, DrSlump.
That said, I also feel it's kind... of... taking the easy route really, it's supposed to be an unimportant backwater planet but almost every single galactic hero worth mentioning has at the very least passed through there once.
And yes, they do it because it's iconic, but every good artist knows when it's better not to use something, and Tatooine is one of those things that should be used rarely, yeah it's an iconic place, but that doesn't justify overusing it.
I suppose it doesn't help that it's basically an easy to make planet in terms of design, lots of sand, very little props needed, you can map out a Tatooine level in a fraction of the time you'd need to make, say, a Coruscant level in a game.
So yeah, basically it's the quick and easy route towards creating a "Star Warsy" experience.