[snarfybarfy]

Taxing excess profits should be somewhat analogous to patents. (Well, except for the huge mess that patents these days are, but I am more talking about the conceptual reasoning behind them).

The creator gets a time limited monopoly to pay for his efforts. Nobody ever thought having an unlimited monopoly was good for society (well except for the guys actually having the monopoly, cuz you know it trickles down somehow).

Regarding the quality of MS products, why it's obvious that they used some of their monopoly rents to hire smart people to work on it.

But the point still stands that they were and still are a monopoly. Otherwise someone equally smart would have broken into their market and pushed profit margins down.