Let's say I want him to feel vulnerable and afraid. But I don't want him just to feel the fear of dying and starting over again, I want him to be afraid on a deeper level.I want him to have a feeling of hope how can I do that
This is the same as any director of film or music, the individuals fit for these positions are separate from the rest of the teams creativty. They have a vision and an understanding of how to create that vision. Being that the industry is so young, I see the designer position becoming much, much more valuable and praised than it currently is. Rewinding the clocks back twenty years, a programmer could do an entire game themself. Five years later that programmer needed an artist. A few more years after that they would need a writer or content creator. Today we have teams working on multimillion dollar projects and a structure to match other forms of entertainment. Not everyone is a game designer, the same as all else. Sure maybe everyone can come up with an "idea" and possibly even evolve it to a workable form, but don't look for another project because chances are it won't be there.
Blizzard learned this to an extent, they recycled much of their content creators for World of Warcraft, creating things such as their raids and battlegrounds.
If things were as simple as "do (x) to make the player (y)" then it wouldn't be very entertaining, now would it?