It’s a terrible business decision. Here it is plainly: if you already subscribe to HBO on your television you aren’t going to watch it on your computer.
What they need to do is open this up to people who watch television shows on their computer primarily, through a combination of advertising support and affordable subscription paywalls. You could have a few tiers for movies & television shows, sports, or everything together.
As NYT’s Media Coder blog points out, HBO GO is part of the “TV Everywhere” initiative being spearheaded by Comcast and Time Warner to provide more on-demand content on the web, but only if you’re a cable subscriber first. It’s not a real solution from these cable companies, it’s a stop gap.
People who torrent shows from premium cable providers do so, not because they are unwilling to pay for the content, but because they don’t want an antiquated cable subscription just to watch the shows online. They torrent the shows because it’s the only option available to watch them.