Well, I understand why they did what they did. It joins a category of games like Diablo 3, where the basic value proposition for the purchaser is fundamentally single player, but the value proposition for the developer follows all the network-effect-leveraging growth-dependent online product tropes. Diablo 3 is especially starkly obvious: the auction house is where Blizzard makes its money post-sale, so they want people playing online. They think it will be better for players in the long run if they are involved in the social and online elements, and they might even be right, but they correctly surmise that unless they force people to be online, people will choose the easy route and play single player.
I don't particularly think they are wrong. For example, after a while, the ridiculous ease of obtaining hacked items ruined single-player for me -- it would be more fun I'm sure to have to work for everything, but I don't have the willpower or incentive to do that unless it's forced on me.
Look at Minecraft. There are multi-hundred player online servers that do great business by providing a persistent world where people have to work for things, making their money by giving diamonds and perks to donors. Not many people play single-player religiously. It's fun for a while, but the main demographic that plays offline is almost certainly the hopeless creatives. (And there's a lot more people who are into competitive/cooperative rat races than are endowed with both a self-motivating sense of design and a bunch of free time.)