Just generally, and very simplistically.... buy this or we scare away your customers.
Errr, um, sort of.....well.... Mafia protection racket, yes?
Put it this way. What is the first thing that springs to mind when some one is scaring off your customers demanding, sorry, politely implying a payment to stop?
Yes, yes, yes, I know. Security, user safety, lots of lovely logical arguments for it, Im sure there are plenty. But strip it back to basics and, well, there it is. I presume since MS is a big huge "evil" business which probably funds some political rodent its all cosy and legal.
Its more complicated, right?