To be fair, a lot of Steam sales are actually so cheap, you pay way less than the worth of the game. For instance, my girlfriend bought me Civilization V and some DLC when it was on sale a bit ago. So I got the main game, tons of DLC scenarios, and every DLC civ for less than $15. The game even without DLC is easily worth twice that.
But sales that big aren't about recouping investments. If you're selling that cheap, you either failed miserably and are trying to recover as much of the damage as possible, or you've already more than made your money back, sales are slacking, and its a way to get some more mileage out of a game people have otherwise lost interest in.
In CivV's case, with an expansion looming in just 2 weeks, it was a way to drum up more interest in the series right before the expansion hits. By expanding the base of people who own the game by selling it on the cheap, it created a wider range of consumers who will have interest in an expansion for that game.
Should anyone consider 75% off sales as part of their normal business strategy? Probably not. But they can be a powerful tool if used with care and proper timing, like in the case of CivV. EA dismissing them out of hand just tells me they're not very good at marketing.