Ask HN: Why do the names of so many products give no information on what it is?

Dropbox makes me think of storage. iPhone is straight to the point as well as Evernote. Of every application you know with a large user base can you tell what the product does by it's name?

So why does it seem that so many companies give up such a valuable piece information into what their product does for a shorter domain name? To sound unique? If there is no connection between the name and the product how likely am I to remember the name when I try to talk about it?