The short answer is, well, no. You wouldn't.
The notion of boycotts stems from the idea that you, the consumer, have a great deal of power in a capitalist market. The good news is, that is absolutely true! The spending habits of consumers has a direct influence on the decisions game developers and publishers make. Just look at how quickly the modern military shooter genre has reproduced in the past years. Do you think that would have happened if Activision hadn't sold approximately 2.6 copies of Modern Warfare to every breathing individual?
I feel like that connection between spending and corporate decision making is generally obvious to most consumers, so why is it that full boycotts don't work?
Simple, it's all in the numbers.
For a company to make a decision based on sales data, there needs to be a clear trend that they can follow. Modern military shooters are selling like hotcakes(sidebar: has anyone ever actually purchased a hotcake?), then produce lots of modern military shooters! No one is buying space sims? Stop making space sims!
Again, all of that is consistent with a fifth grade understanding of corporate marketing. But what happens when gamers institute a boycott? If a large number of gamers stop buying EA products completely, the end result will only be a decrease in yearly profits for EA. Will it punish the company? Sure. Will it make them change their practices? Absolutely not.
If a companies sales data shows decreasing sales for everything, there's a much smaller chance that they will change anything.
Lets look at a couple scenarios, regarding the recent SimCity DRM riots.
Pictured: EA's PR Division
But lets say that gamers hear about the many DRM issues with SimCity in advance of purchase, and decide to simply avoid buying that game. But without a full on boycott, they continue to buy the titles they still enjoy(with less obtrusive DRM) from EA. At the end of the year, EA will see that SimCity performed poorly compared to the rest of their releases. In this situation, you can be damn sure they'll be looking in to every possible explanation for this loss of profits.
If you disagree with EA's practices with DRM, all you need to do is stop buying any game they release with obtrusive DRM. Trust me, it wont be long before they notice a trend.
The only way that you as the consumer can have an effect on the market is to follow this simple dictum: buy the stuff you like and avoid the stuff you don't. This has to be done on a game-by-game basis, and it contains no room for biases against specific developers or publishers. If a game does something you disagree with, don't buy it. Motivating your spending based on anything else is only hurting your cause.