Democracy treats every member equally. In this case, 5 member have got special privileges that are not shared by other people. If veto is supposed to be important, it should be shared by all members and there should not be 5 permanent members at all.
People who argue that there are small countries and then there are large countries should also not that veto is given to the 5 countries that are neither the largest in terms of size nor the largest in terms of population. It is in fact given to the countries that were most powerful in terms of military strength when UN was formed. So basically, UN security council is ruled by a small group of people who have absolute power and were not elected to their post by other members and just assumed the post based on military strength. This resembles a dictatorship more than democracy.
Well, it boils down to the five permanent member of the security council. The temporary members are just there for consulting. If even one permanent member of the security council vetoes a resolution, its rejected and forgotten. Last time I checked, the majority wins in a democratic society, not the minority.
At the end of the day, it comes to the permanent members of the security council to decide upon a resolution. If even one permanent member out of the five rejects it, then the whole resolution is dropped. How does this serve the principle of democracy if the majority never wins?
One look at how much of the UN votes and speaks is all it takes to understand how important a Security Council veto is. Its relatively easy to amass a large number of votes in the general council, due to the large number of small countries; while many countries vote and speak, very few countries in body bear the brunt of the cost and political response from such votes. Any serious resolution backed without the world's foremost powers (largely represented in the council) would be largely ineffectual in any case - a veto allows a vote passed to at least have some legitimacy.
The veto power does not violate democratic principles of equality. The veto power actually provides democratic principles to the council. The veto gives voice to the minority. The veto also allows for the dissent to show it's side. All sides views being known, allows for discussion which can lead to resolve.
Having a veto power on the UN security Council does not violate democratic principles of equality. The veto gives one a chance to voice opinion giving equal voice to everyone on the council. This gives everyone a chance to work toward an agreement everyone agrees to. The idea of democratic principles.