Well, that’s how it goes nowadays. Microsoft is bringing everyone under the corporate umbrella, and culling the weak while they’re at it. EA is the innovator in that sector, and it’s no surprise Microsoft is following suit. Microsoft Game Studios has laid off all “non-essential” employees from Ensemble, and will lay off the rest when Halo Wars is released. After that, some of the higher-ups will be reintegrated with MGS.
Ensemble was one of the reasons I became interested in videogames at all, and while I never thought I’d work there, it’s a bit like a mentor dying. A lot of the forum communities and clans I’ve been a part of came about as the result of Ensemble games. Now it seems like Ensemble is just an old, loyal dog that Microsoft has to take out back.
Sure, there’s money involved. MSG is just a part of Microsoft and they have to carry their weight financially. Business. And if Microsoft Game Studios can’t afford to support, well, a game studio, then either someone is making up for losses elsewhere, or Microsoft has seen better days in the game market.

More information on the closure can be found here: http://www.gamasutra.com/php-bin/news_index.php?story=20178