MS is not scam. I personally look at it as somewhat cash withdrawal. Since nowadays not too many people do a traditional cash withdrawal, banks lose some potential profit here. With MS, the opportunity to make some profit for banks came alive.
It`s not like you are stealing money or do something illegal with it; you are purchasing travel perks (and keeping travel industry afloat) and splitting the cost with banks. We all spend money on MS in some way-some people more, some people less, but we do.
Every store (especially their managers) is happy to sell gift cards, too, as they have to meet a quota.
I see it as win-win situation for all.