Why is Google Calendar lacking a tasks list?

Well, I know this is something that has been brought up a lot in the past and is one of the most requested features for Google Calendar. Yet, I have never found a definitive answer or even ANY information of why Google just doesn't want to add this feature to Google Calendar. I *DO* use "Remember the Milk" with Google Calendar and while it works great I just don't understand why I have to use two different services for such a simple task (no pun intended)!?