>That's certainly true for Google or Amazon but not for most real corporate IT departments.

I can't speak for all corporate IT departments, but I'm at a very large corporation that certainly cares about idle power consumption. Over the years our servers have gotten more powerful, and more power hungry. It's not that hard to add more power, but adding new cooling isn't so easy. The less power we use overall, the less cooling we have to add, and the happier we are.