Democracy is also about protecting individual rights from the tyranny of majority. That is the case for blacks and gays being discriminated by the majority, as well as wrongfully accused being railroaded by the criminal justice system.
As for progressive tax system and the welfare scheme, neither democracy nor dictatorship could resolve the conflict of individual property right and the need of the poor mass. At most in democracy you have the free speech and freedom of association to carry on political activities against the existing system as you see as unjust. In a dictatorship, if you don't like the tax system or welfare system, you can't say or do anything, and the dictators keeps filling his pockets.
