Look at any products, cereal, cars, soda, anything, its gonna be one word because thats how marketing works.
Cereal was a bad example.
Cinnamon Toast Crunch
Count Chocula
Boo Berry
Lucky Charms
Waffle Crisp
And those are just ones I like.
And in sodas you can find examples as well.
Mountain Dew
Vanilla Coke
Crystal Pepsi (and you can't tell me that failed because of the name)
Having one word is usually the easiest route to something catchy, but it's not the only one. Besides, if one word was the ultimate way to market an effect, it makes you wonder why so many multi-syllabic products still sell consistently well today or how they even managed to survive this long.