It's amusing how relevant the chap I have in my avatar rotation is to this thread <.<

I'll see if I can find the quote about this <.<
I also have to go for a bit so it might be a while before I reply with it >.>

Why is the actual more important, why does it command more immediacy, over the non-actual? Why is the real more valuable than the wishful? Why is the matter-of-fact considered to be of a higher nature than what we should like to be true.

Assuming no atrocious or magnificent outcomes from choosing one over the other, what gives a truth more value than a falsehood?

Well I can't find the quote I was looking for but Byrne posted the most relevant part of it.

As a serious answer, I would say it is because making a judgement or decision on false information nearly always leads to a negative outcome. Something that is true is something that the majority can agree on and accept as reliable information, allowing decisions to be made about it that would have less of a risk.

The trouble is, when a lie/falsehood is widely accepted as the truth it can then disrupt the above statement. Or if something is widely accepted as harmless - like smoking or asbestos - when the truth comes to light that they are both really bad for you, the damage has already been done and many decisions have been made on a falsehood - that asbestos is fine to use for insulation and that smoking is good for you. And we can all see the consequences of these falsehoods today.