Of course it makes financial sense for the business. Taking the customer's money and not delivering the promised product is really profitable, if you can get away with it.
Still a dick move though.
Microsoft could make a deal with, say, Apple. They check each Microsoft Music (Xbox Music? Zune Music?) account for total spend, and give people an iTunes gift card for nearest total amount. Negotiate a bulk pricing deal with Apple.
Microsoft gets to look good, Apple gets to look good. But it'd cost 0.001% of total Microsoft profit and the shareholders can't have that.
Compare that to some other businesses that will happily recommend you to a competitor if it is a better fit, or if they shut down go out of their way to write a tool or help you with off- and onboarding to an alternative.
What you call a dick move might actually have made sense financially for a business. If MS Music was losing money with no hopes of ever turning a profit, why should they continue to operate a charity music service subsidized by all of the other MS businesses that are making money?
Same thing for Amazon. If it is something that shows no signs of paying for itself, why continue to operate it? You have to stop the bleeding at some point. What was the attraction to a dev to use Amazon over Google? Lower percentage of the take? Maybe that explains why it was a money loser?
At the end of the day, it was a bet on a losing horse.