No other commandment, not kosher laws, purity, even murder, does it say keep your distance. Why this specific law?
Perhaps it is because lies have a supernatural ability to hide the truth. A murderer is a murderer. The sin is obvious. Eating forbidden food is a visible transgression. Purity laws as well. Their is a visible line that one must cross in order to transgress any of these sins and we are able to enact laws to further protect ourselves from transgressing them.
Lies are unlike any other transgression. Slander and gossip are about others and can be quantified. But a common lie is something that once released can turn reality to fantasy. The lie takes on a life of its own and can become believable to the person that created it. We can lie to ourselves as easily as we can lie to others.
As Rabbi Rothstein notes:
"Do we become attached to our own views, and stubbornly resist countervailing evidence? When we witness a debate, do we help one side over the other, regardless of the truth? Do we allow appearances (or money) to sway our picture of who is right and who is wrong?"
Once we get used to being lied to for so many years, the truth seems foreign because we did not distance ourselves from lies at the outset.
Here is hoping that with some current changes and many changes coming in the future, we can push aside the lies that we have been told all these years.