You can make the same argument against minimum wage, or any other abusive contracts (payday/predatory loans). A lot of time one of the party signing the contract has no other option depending on his situation, that doesn't mean a company/individual should be able to take advantage of his situation and get him in a tough bargain.
Also, not all contract signings are created equal, that's how a lot of companies sneak no-compete's which have been deemed unenforceable many times.