democracy is still "majority rule" - you can debate and try to change opinions, but it still comes down to vote, and people often vote "yes" on issues that debate clearly points to "no" on.
but we don't have democracy - we have a democratic republic, where we by popular vote (not by debate) elect representatives. representatives who still often don't do what reflects majority opinion. if majority opinion was always honored, like Des said - we would have legalized pot, socialized medicine and a higher minimum wage in every state, and congressional term limits, for example. we would never have gone to war in Iraq, or Vietnam, and there would be campaign finance reform, and corporations would not be considered people, if majority opinion and reasoned discourse decided national action.
"we the people" don't decide issues. elected representatives do, and they make decisions based on a lot of influences other than majority opinion or pure reason.