I was using gnut and other clients (I don't remember their names, - it was some dead projects for gtk but it was not gtk-gnutella) before I even noticed their was any such thing as Limewire or Bearshare. So there probably would be a gnutella without Bearshare or Limewire although I doubt the network would have grown that fast.

As for ads - people, probably using ICQ, GoZilla or surfing web sites with banners shouldn't even start to complain about ads bundled with LimeWire (at least the information gathered by spyware is not shared with governmental agencies, is it?).