Think of it this way, a homepage is kind of like a storefront that people can choose to enter or not. A store that sits on Broadway in New York City is going to be worth more than a store on Pecan Street in Pflugerville, Texas primarily because it has greater traffic.
More traffic = more sales = more profits = worth more.
Of course, then we get to the question of whether the traffic is quality
traffic or not. In other words, if you acquire a domain name from an out of business baby store that is listed in DMOZ, yahoo, MSN, Google, etc. , you will have a better chance of making a sale if you put up another baby store website, or forward it to an existing baby website, or PPCs for baby related items. If you put up a porn site in it's place, you'll probably get alot of complaints to those search engine/directory sites that will get you dropped sooner... (and how could you sleep at night scaring all those new moms.