I'm sorry, but the problem is that PLA won't decompose in landfill. The commercial composting conditions needed for this material to degrade fully aren't present. That's not to say however, that PLA is a bad thing - it really does have a great value, but we need to develop schemes which will extract that value by composting.
We need to increase the use of PLA used in our society so that it becomes financially viable for recycling.