Book One In What Series?

Okay, it's like this. I read a lot of books that are in a series. In fact, I probably read more of those than I do stand alone novels. I like series. As long as they don't continue endlessly, but that's a post for another time. But I've been wondering something a lot lately.

Throne of Glass - Book One in the Throne of Glass Series
The Emperor's Edge - Book One in the Emperor's Edge Series
Falling Kingdoms - Book One in the Falling Kingdoms Series
The Green Rider - Book One in The Green Rider Series

What do all these books have in common? (Many more do as well, I just stopped there.)

All these books have the same title for their series as the first book in the series.

Once I started thinking about that I started wondering, why do so many books do that?

The first idea that came to my mind was the extremely uncharitable 'they can't think of anything else to call the series'. Then I started wondering if, maybe, the author/publisher didn't know the book was going to spawn a series and when it did, they just went with the obvious. Maybe, and this is probably the nicest of my ideas, it was decided that having the first book and the series bear the same title would make it easier to remember.

Oddly, there is one series that was really odd in how it handled this. Book three of the series (The Magnificent Devices) had the same title as the series. The two books before that and the, so far, four books after that had a different name. This lead me to believe this series was only supposed to be a trilogy.

Anyhow, what do you think? Any odd series/book title correlations you'd like to mention?