Well she really didn't have much of an option at that time. Left Romefeller continue it's military reign over the Earth and colonies and ceat more inside 'coups like with the Treize faction or make a drastic change. I know she was Queen, but she had those Romefeller heads that seemed to talk about plans along with her, so I doubt she was alone in coming up with that plan.
I don't disagree with her being naive and somewhat fascist. But fuck, who thought it was a goo idea to instate a 15 year old girl with little political background as the head of the biggest military and political power in the world. Of course she's gonna be idealist in her decisions.