No doubt about it, "Yertle the Turtle"is the meatiest story here, so it's no surprise that the title of the collection is pretty Yertle-centric (and we're betting Yertle didn't have any problems with that). But those "other stories" are just as important, despite getting "other" stuck next to 'em. Since they cover a lot of the same things, they're kind of like Yertle: parts II and III.
But don't think for a moment that each story isn't a story worthy of its own name, because, as you can see inside, Seuss actually named all three. So what does the title for each of the stories mean? It means, "Hey! This character or idea here is the most important!"
"Yertle the Turtle" is about Yertle and how much it stinks to have him around. "Gertrude McFuzz" is all about Gertrude McFuzz and how vain she is. "The Big Brag" is about, well, characters that brag a lot. It's not rocket science here, folks, but it is a little more complex when you think about all of that ego stuff we talk about in the "Illustrations" section. Yep, every title revolves around the character or act that best expresses the ego. Surprised?