it's a question of which pirate channel you want to stop.
1) the "hey chris, want a copy of this new game I got? It's great and there is no protection"
2) the "Arrrr, we've stripped out all the protection so you can now put a copy of this on yer hard disk and make easy backups"
All games should have *some* method of trivial protection to stop case 1 because it destroys sales. Most people are immoral when they are anonymous.
The most effective protection I've ever seen is new content created by the developer on their web site that the game must phone home for. It must sign in with a unique id and after a couple successful downloads, that id is locked until the next content release. The protection is on the server side.
I would recommend the following model.
1) Create content on the web site that must be downloaded with an ID that updates the program as well. Tightly integrate the downloaded data with the multiple gigabytes of data that already exists. Don't be an idiot and make it a stand alone 2mb file.
2) Set an arbitrary date when the content will stop (12-24 months) and the game will be unlocked due to an expectation that sales will drop to a level that support for problems is impossible. At that point, make the game unprotected and get good will and trust from your customers. And even then, you'll still get new sales- but the main wave of "hey chris" copies has passed.