Unions are necessary in order to guarantee worker's rights: especially in developing countries. However, as other posters have said they can, like any organisation, have a little too much power. In the balance of things, I'd certainly prefer to have more powerful unions than ineffective ones, as the ideal they represent: collective bargaining, empowers the masses and in a world with a rapidly growing gap between rich & poor, such action will become more and more necessary in the coming years.