Why is there a dialog "Your download will start in 5 seconds" on many sites? And they even always provide direct link. Why not just point browser directly to file (which always works perfectly for me)?
If you want to make your download server, you must have some profits without premium members.
In some cases, not all, it's so that the site can display some ads for a few seconds more. If you will have ads on your download server, you can deter the uploaders and downloaders. Most it's for premium membership.