It's not entirely rational. I just find the practice offensive (like the urban "facility fee") and want to do my (very small) part to discourage it by not booking hotels that do this.

I also tend to have an unpredictable schedule, cancel a fair number of reservations, and don't want to hassle with keeping track of refunds. Because you know some percentage of the time there's going to be an error by the property and it will always be in their favor.