That's a hard question to answer, but I'll try to explain it as best as I can.
Back in 2007, John Riccitiello became CEO of Electronic Arts. His return to the company after leaving was dependent upon a few factors, one of them was increasing sales and profits at the demand of the Board and Shareholders.
Electronic Arts, along with other Tier 1 Gaming companies like Activision, don't actually "hate" used games, they're just extremely greedy. They saw that there were numerous amounts of people who were simply renting games or buying pre-owned instead of forking over $60 for their sub-par games. Being at the beck and call of Stockholders, they saw this as an opportunity to profit.
Companies have used Serial Keys on PC Games for years, but Piracy on the PC was too big to make it matter, which is why most Gaming companies refuse to even publish on the PC or they'll delay the PC release to weeks or months after the console version launches.
The Online Pass was originally planned to be the same as PC games, requiring an entire Serial Key to even play the game. Unfortunately for them, when they did a Focus Group and polled them, they found overwhelming backlash at the idea. Undeterred, though, they thought of ways to introduce it because they felt there was sufficient profit to be made in doing so.
They decided to introduce it as just a Multiplayer component, since this was the core of the Gaming market they wanted to corner. They knew they'd upset Gamers, but they also knew that people would eventually come to accept it and submit to it, which they have. The idea, in reality, is to slowly introduce ever-increasing restrictions to test how consumers react and gauge their response for the future.
Through slow introduction, by locking out Multiplayer, they have now moved on to Single Player restrictions like the games RAGE, Batman: Arkham City, etc. Activision has taken the lead in a new study with the Call of Duty: Elite, which is a study of how people will respond to a subscription-based service. This service, in their eyes, guarantees a steady stream of income from Gamers.
Unfortunately, Gamers seem to have accepted and submitted to that as well, forever changing the landscape of the Gaming sector. It's going to be interesting to see the next step in the process, as it will no doubt upset Gamers. But, if the past is any indication of the future, nothing good can come of this.
I don't see why Gamers are defending companies like this, saying that it's okay to do it because things are "optional" and aren't "shoved down your throats" like some. This logic is heavily flawed, because with each new restriction the Game companies get bolder and bolder, inching ever closer to the final step of having complete activation of Console games.
I hope that never happens, and I don't see how it can based on the article I wrote before this, but the future will tell.