"Toy Story Mania" to me seems like a cop out way to milk a film into an attraction. And it also doesn't really describe what it is you're riding. What does "Mania" mean? Is it a roller coaster? Is it a dark ride? Is it a new show? It's incredibly vague.
"Toy Story Midway Mania" sounds like an effort to make a ride with an actual theme while using said characters. Using "midway" is just an extra touch to allow it to fit in a lot better into its environment as well because it really is out of place in Disney's Hollywood Studios.
And on a tangent, I was never a fan of the 2D illustrations of the Toy Story characters.