If I were to set up a shop down the street and sell your property without your consent, I would be violating your rights, wouldn't I? Of course. Well, what if I got the majority of the city to say that I could sell your property at my store? I mean, majority rules.
What if the duly elected government decided to violate your rights? What if we needed a new hospital built and it made the most sense to build it on your family's land; the land that had been passed down in your family for 200 years, the land where your grandfather and his grandfather were born, raised, and died. What if were a road that was needed? It's ok, they'll dig up gramps and move him. And you'll get "market value" (which is bullshit, because the only market for your land is your market and by forcing you to sell it below any price you demand is not allowing for market value).
So....what if it were a shopping mall? Wal-Mart? Jail? Nissan Factory? What if they just wanted to take it and turn it into a parking lot?
What's to stop them?
Our Constitution? I'm afraid this is all that's left of our last line of defense against the tyranny of a well-meaning majority.