Tizzysawr: I'm not sure they made much of a profit. Remember all sales during the first month, which is the biggest month for sale and probably accounts for at least 1M of those sales you mention, were "refunded" by the way of giving people another, new, shiny EA game. I myself got Dead Space 3, which retailed at $60. If EA did its books by subtracting the full cost of these games to what was earned from sales numbers will have gone down quite a lot.
Then, regarding the DLC: There were smaller bits and an expansion. An overpriced expansion I refused to buy and that many people considered good, yet lacked to address the issues with the base game. Development of the base game, on top of that, was extended by many more months to try and address the many issues the game had or how it failed to deliver on its promises, adding extra expenses to an already expensive development process.
Now, EA probably made some money from it, that's true. But considering the debacle the game was and the myriad of bugs and other issues it had, would you really as a CEO want to keep that company around after that?
I don't know what games they gave away, but probably all of them were outside the golden first month of release (which is the only month most publishers seem to care about). Which to them means that you weren't going to buy those games anyway and the loss is very minimal. Don't forget that it costs them next to nothing to send out a bunch of Origin keys. In fact, given that games like Dead Space 3 have microtransactions, they could even have made money doing that.
When an AAA game is in development they usually have 100 or more people working stupid hours trying to meet the deadline. How many people do you think they had working on the patch? How long do you think they actually spent on it in terms of man hours? Don't forget that the central problem was easily solved by just one customer very quickly who didn't have any source code - just a retail copy of the game - to work with. OK it wasn't perfect, but it just needed polish by people who knew the game better and had the source code. Which Maxis did.
In terms of man hours we're talking sod all here.
No, I don't see EA wanting to keep Maxis around after Sim City. But more because of the other failings that had nothing to do with the DRM than because of it. It simply wasn't up to scratch in any sense. The DRM just finished it off. After all it's perfectly reasonable to assume that the DRM was imposed by EA.
In any case, Maxis fucked up and not for the first time. That, coupled with the fact that EA just likes to close studios, is why they got shut down. Not because they didn't make money.