The reasoning behind this was that the link must be maintained with full bandwidth signaling so that it is ready to support data transmission at all times.
In order to save energy during times where there is a gap in the data stream, EEE uses a signaling protocol that allows a transmitter to indicate that there is a gap in the data and that the link can go idle. The signaling protocol is also used to indicate that the link needs to resume after a pre-defined delay.