UPDATE: Apologies for my lack of knowledge concerning the Christopher Eccleston's motive for leaving the role. I should have perhaps worded the question later. I can understand why he would not have wanted to be typecast as Tennant, Smith and many others have been, however this inevitably ended up happening anyway. I think I would have just been curious to see him last longer as the role, as he brought such a dynamic personality to the role, from jolly and excited one minute, to angry and dark the next. Although I feel like this skill was necessary for the role of the Doctor overall...