Julie: However dodgy it can become when you centralise power, unions and the links to labour were set up like that as a worker-based (at least theoretically) counterweight to the influence of money on the establishment parties. The block vote of being able to hire lobbyists, or just pop round your chipping norton mates' house is much worse a problem. I'm mostly not a fan of the current unions which seem to be a bit selfish and lacking the concept of solidarity (apart from bob crow (peace be upon him) and len mclusky at a push) - i'm all for the wobblies (IWW) method though (ie just have one big union for everyone (and anarcho-syndicalism) - pretty much illegal in britain now).
Droppersneck: A more 'libertarian' green party (in the way i think you mean) would just be the same as the tories: saying they want to save the planet, but not wanting to impinge on the freedom of everyday people (meaning billionaires) to actually do anything. While libertarians (at least the american influenced variety) think government is the worst thing in the world, getting popular control of government is the only way the majority of powerless people have any chance of protecting ourselves against the power of wealth (however small a chance it seems right now). I'm an anarchist, so ultimately i would want to get rid of centralised government and replace it with bottom up direct democracy, but until we're anywhere near that, government is often our only protection - if that protection has been diminished over the last decades, the answer is to fight to get the power back; not let the foxes completely run the henhouse.
Libertarianism just accepts that the people who happen to already be massively rich should be able to run the world and there's nothing anyone can do about it (this is always how the 'free' market works) - but it's alright cos i can own a gun, i don't have to pay tax or not say nigger (but i still live in a hovel with no water supply or electricity cos they're unprofitable). Plus if someone like charles kock, ayn rand and ron paul want something, i'm pretty sure it won't be good for people like me and (i assume) you. Feudalism didn't work out so great for the peasants last time - i don't suppose neo-feudalism will be any better.