EJ_1974, your last post changes the whole topic of this discussion quite a bit (and actually makes it even more interesting).
I for one would be against it as I think it is silly to "force-supplement" the whole population like that. I have a thing about everyone popping pills these days(and adding powders to our food supply is no different). Having said that, I do take a prenatal vitamin (elevit) but that is my choice and in general I try to get my vitamins from natural sources rather than artificial ones. I don't know if I make much sense, but I think that taking supplements should be an individual decision, just like any other medication and sneaking them into our food supply is an interference that I take offence to. I don't even like the idea of fluoride being added to our tap water.
The main reason for me being against it is that it doesn't stop with folate. If we get into a habit of doing that, every fad will end up in our food and it might even include some substances that might proof harmful later on. The other issue is that it might be easy to overdose on various vitamins as you might get them in say your bread, milk and then again in your breakfast cereal.
And another point is also that there are huge quality differences between one artificial vitamin and the other. So you don't have much control over what kind of quality you are ingesting. And they are never as good for you as they are if you get them from natural sources.
I guess, I want to be able to make informed choices.
And nowadays most women who are TTC know about the importance of folate and take it as soon as they find out they are pregnant or even before. Of course there is the problem with women who fall pregnant accidentally and don't realise before it is too late. But in those cases folate might not be the only problem. They might have been drinking and smoking and taking drugs, eating raw eggs, raw fish high in mercury, bla bla bla. Are we going to control that in the general population aswell, just in case???

Anyway, I get off my soapbox now I hope I didn't offend anyone. I know spina bifida and anencephaly can be very serious (if not fatal) problems and I don't want to make light of these conditions. I just think that every woman has the right to choose what she puts in her body.