Something has changed though. Previously, i might consider shelling out for a copy of MineCraft (I don't play it at the moment, in fact I don't really seem to have time to play anything right now), supporting independent developers and all that. But just the knowledge that the money is going to MicroSoft might make me think twice.
As for people asking how Microsoft will manage to wring $2.5 billion out of Mojang: they don't really have to, because that's not how investments work. They had all this cash lying around doing very little, they've exchanged it for something of value that creates a revenue stream. Plus, that thing (shares) maintains value in and of itself.
Realistically, they'd expect a 5-10% per-year return on that money, and that can come from both sales revenue, outsourcing work from Microsoft to Mojang (they can shift game dev stuff from in house to Mojang making it more efficient) and increases in the share value of the thing they bought.
Plus, if the value of shares actually falls they can then declare a loss for tax purposes. So they might even make a windows phone minecraft and make that shit a FREEBIE that comes with Windows Phone. Looking at the long game, boosting Windows Phone with popular free apps would be worth taking a loss on Mojang, which could just be written off on taxes anyway.