Then why attempting to avoid the mess Aurora planned to do.
Another thought, if Power is all that count for the Fea, why winter tried to stop Aurora plans, if she succeeded they would have got massive amounts of energy/power.

Aren't they all power hungry ?

Mother Winter is a Fae.  Fae in Butcher's mythos seem to operate as elements of creation (by that I mean reality) itself.  They have a place in it.  Mother Winter doesn't want to destroy things.  At least, not before their ordained time to be destroyed.  Hell's forces seem to want to destroy things early.  They want to wreck God's plan, as it were.  Mother Winter is simply acting according to her plan (God's plan I suppose, since God created everything, but I digress).