Before this I had no choice.
For example: it seems that when I connect to one BearShare node, then others connect back till I have nothing but BearShare nodes connected. (I am using Gnucleus)
I search and most of the results come from BearShare nodes.
I don't know about you, but BearShare people don't seem to know what good music is. I have my own tastes you know.
So now I can selectivly block BearShare or Morpheus, or even Gnucleus and move around the network to find my music or any other rare files.
It's so nice to have that choice!
If I hear something on the forums here about a client getting greedy, or spying on it's users, I have the choice to block that client and not support it by letting it use my computer network resources.
When I hear that that client has removed the spyware, I can simply change a few settings and that client is not on my bad list anymore.
Power to the people!
If I hear that a old client is creating a problem for the network, I can simply add it to my list to help the network without waiting for a developer group to decide what to do.
What could be so wrong with giving the users a choice?