Well, if they save enough money to only pay for the salary of the dedicated Anti-Bot Squad, then it's a net benefit as they also get the PR value of looking like they care. As you say, there's a cost-to-benefit ratio that has some tangible metrics and some intangibles. The interwebs mob rarely considers that as the player's view from a monitor in a 3-D game tends to be pretty myopic. I'd hate to be in the support team for a major game studio.