Bruce Straley explained the reason behind his departure from Naughty Dog.

Straley, the director of The Last of Us, as well as the co-director of Uncharted 4: A Thief’s End (the other director being Neil Druckmann, who now heads The Last of Us Part II’s development), participated in Kotaku’s Splitscreen podcast. He said the following:

„Uncharted 4 showed up, and it was like, I guess there’s a difference between doing something for yourself which feels passionate–and I had my theories that I was trying to expand upon between Uncharted 1, 2, and The Last of Us–and then Uncharted 4 became more like, ‘How do I do this for the team and for the company?’

We needed to get the game out the door, and we needed it to be something good so that it didn’t put a mark on the Naughty Dog name. I felt like; I guess in hindsight I took on that role more for the team than for me personally… Two years to create that beast, that then became the hardest project [I had worked on].” As a comparison: The Last of Us needed four years (2009-2013)!

Why did he leave Naughty Dog? It’s not because of the team or their games – he just felt burnt out after Uncharted 4: A Thief’s End launched, and he felt like he needs a break. He felt stressed under the development, which felt more like an obligation instead of a passion project.

Source: Kotaku