Gnucleus is released under the GPL which puts Gnucleus's clones and any changes they've made under the GPL. The whole point in the GPL is that changes get made available and contributed back to the community. So why not make use of the changes that the clones make. And if all the clones are doing is changing the icons then sift through the 10+ clones and cherry pick any nice icons they have and put them back into Gnucleus.