See Requeries (click on link) as this explains why it's not a prefered option. Resuming all your files at once will add a dramatic amount of traffic to the network. If everyone did this then the network would slow down considerably. And that would mean much slower searches, slower downlds, slower getting connected, etc. The gnutella network is different from other networks & doesn't want to make the same mistakes some of them have made.

I must say the resume function was more effective in earlier versions. But using the search function is even much more effective. Choosing the right file to downld with lots of sources & not too many downlds at once also helps.