1. Why ask US? The terms and conditions of the program are publicly available on its website and make it clear that US can change the program at any time and without notice.

2. Why would this be unethical? When you join MP, you specifically check the "I agree" box noting that you have read, understand and agree to the terms and conditions in #1. It's a voluntary program, costs nothing and is upfront and transperent about its terms. Those are the hallmarks of business ethics.

3. As to whether it's good business, only US knows the numbers, but presumably an improved economic situation leading to more purchased premium seats, coupled with capacity cuts, means that there's no reason to give those seats away at such a low "price." Miles are no different than dollars. When demand goes up, US raises its prices for revenue tickets. Makes sense to do so for award tickets too.