Look at it from Rockstar's point of view. They're a business. Their aim is to make money.
The amount of money they will potentially lose to piracy by not including DRM is SUBSTANTIALLY more than the amount of money they will potentially lose due to the small percentage of gamers who refuse to buy it because of DRM.
So them, it's probably well worth it.
If Ubisoft's financials are any indication, the amount of gamers passing on the game due to bad DRM is higher than you think, and the amount of pirates legitimately buying the game is much smaller.