It's a nice feature, especially when there is no vacation flag available. I suspect the vacation flag is easier to implement, and requires fewer server resources. Either would be a welcome addition to prevent timeouts.
it would be very helpful especially if you have to good players playing each other and one knows what the other is going to do. it saves time and helps everybody, i guess it would be just like playing the computer as you could end up having 5-6 moves waiting you. It would be a good feature aswell as flags which i suggested when the forums first began.