Actually, this ruins 401k plans for folks who stick with the company too. Employees miss out on all the compounding throughout the year from the contributions.
From WaPo:
"In other words, employees will have to stay through the end of the year to get the match, and then the contribution won't even come during 2014. In a year like last year, where the stock market was roaring, the difference for an employee who left in December could amount to thousands of dollars in pay and added savings."