What about if, say, you have one file that is slowly downloading and is already at 70%, and some other files that have been "Awaiting sources" for a really reeeeeally long time? What would happen if the guy that had one of these files suddenly, after all this time you've been waiting for him to get back online, reappears with a great connection, allowing you to get his file in minutes?
The one in 70% would take priority and you'd lose your chance to get that file and would have to wait, again.
This could be really frustrating.
