More important is the company match
Places like Enron, my former employer, and other high-tech companies give 100% of their match in company stock. So while you, the employee, can diversify your contributions into several funds, the company gives you nothing but empty promises. It costs them nothing to issue stock and give you some once or twice a year since it's really nothing more than an accounting manuever in some digital account. After all, you can't sell it until you're 59 1/2 anyway.
My take would be a regulation that forces the company match to be at least 50% cash that you could put into any or all funds available in the plan.
