I would argue that EEE advertisement on the PHY should be enabled by
default.
That is an open question at the moment. For some use cases, it can add
extra delay and jitter which can cause problems. I've heard people
doing PTP don't like EEE for example.
The current phylib core code leaves the PHY advertisement whatever its
reset default is. So we leave it to the manufacture to decide if it
should be enabled or disabled by default. It is policy, so it should
really be down to user space to configure EEE how it wants it.