Hey, cool, vudu quoted me!
But anyway, I'm not surprised that the most common nouns are one-syllable. But then again why complicate things? When man started with language and started naming things, it's not like they were going to overcomplicate things. Even if they did, by the time English came around, laziness probably ensured that we'd use "dog" over "canine" and etc.
Even long words and phrases are likely to be shortened over time. No one even says something as short as "What is up?" when they could say "What's up?" then "Wazzup?" or "'Sup?" Next thing you know we'll just be saying "Up?"
I notice there are a lot of movies in the past decade that are just one word, or "The [___]". No one ever makes movies with crazy titles like "Attack of the 50-Foot Woman" anymore.