One might say it's unrealistic to expect everyone to agree on one thing, but how realistic is it to change laws every few years and months on issues that are entirely personal and cultural?
People often get thrown in prison for terms that last longer than it takes for the crimes which put them there to become legalized. Our system of law-making is completely schizophrenic.
One could argue that consensus poses a problem similar to democracy but working in the opposite direction: The smallest minority could prevent real progress. But if one keeps in mind that small, localized group negotiation is the most effecient way to deal with most minor issues, there is room for compromises of all sorts. Negotiation is the key word here. Nothing has to be finalized. Dissenters could reason with the majority to have concessions made for them, or compromise on getting what they want in some manageable form that doesn't disrupt anyone.
It sounds like a lot of planning and talking but it's quite organic. Think about how things get done between you and a group of friends. There is consensus where possible, and where that doesn't work, small scale negotiation. Greater society could work this way concerning most issues. Compromises can only reasonably be made when you can look someone in the eye and know where they're coming from.