How does Heroes Feast work in Pathfinder? Does it still negate fear and poison?
I think that alone is one of the reasons why I think the Warforged immunities are not a big deal. They might be from the perspective of the game world (not needing to eat is obviously useful for a soldier - even for a peasant, actually), but they don't affect the game balance much.
The "trick" with poison or disease immunity is that it is typically something that affects the entire party, not just a single character. The Warforged can't be poisoned. The Elven Wizard and the Human Cleric still can be. You still need to spend those Lesser Restoration or Restoration spells to deal with it - or spend a few days recovering the ability damage or traveling to the city where you can get the ability drain removed.
Similar - a Warforged not needing to breath is only of help if only he has to deal with the lack of air and the rest can ignore it. If not, he gets the honor of doing whatever needs to be done without spells - but also the risk of going alone.