Why is it important to know the truth?
Let's say we're living in the Matrix or Plato's cave. And thus you're being tricked and don't know the truth about reality.
Now, let's say you don't know this, but you have some intuition that this might be the case. Why does it matter? Would it change how you live, how happy you are? Note I am not just talking about truth in the metaphysical sense, but also in things like knowing the truth regarding certain things that did/n't happen: did your ex lie to you? Does this person really like you back?
Is knowing the truth good in itself or is it a practical question of having the information you need at hand? Or does it not matter?
If you were content not to look outside the cave, you couldn't be sure that a demolition crew wasn't on its way to blow it up. Perpetual bliss is also perpetual insecurity.
I think most people would be unhappy to think they're being deceived. Even if you could disregard xerxe's point about insecurity and somehow be assured that you were safe, I think that wanting to know the truth is such a basic human desire that almost everyone would prefer it.
As an enneagram 946, I must say the search for truth is what leads me to doubt myself and get nowhere. I could choose to doubt that someone has positive relations towards me, but it wouldn't help me any bit or affect my actions or my interest in the affecting my relations towards them.
I'm usually content with not knowing everything, as long as I can act positively on my assumptions.
My output depends on the information that comes in, so regardless how unhappy it makes me I want to get as close to the objective truth as possible in order to generate output (action) that is in line with reality. Following my intuition will change my life, it will eventually lead me out of the cave and into a much bigger world.