It's not so easy out in what my boss calls the "real world." People ask questions. At some point, though we don't normally teach them so, they realize that things don't have to be the way they are just because they already are. The question "why?" is no longer synonymous with "are we there yet?", but actually demands an answer.
If you don't have a reason, and if you have a policy of not having a reason, you can get away with just about anything. Employment policy? You can fire someone without reason, so you do. Sure, it was because she was too gay for your taste; but if you're not required to have a reason, you get away with it. Feel like making a law against your neighbor masturbating? Does it gross you out to think about what he does in the morning? Fine! You're not required to have a reason; so long as you can get enough votes from like-minded (and like-reason-lacking) people, you've got yourself a law.
That which has no reason cannot be attacked on grounds of logic. You can't use as justification the fact that circumstances ("the times" as we call them) have changed, because the context of the law isn't included in the law itself. You can't claim that the law was based on false facts because those facts aren't included in the law. You can't prove that the law wasn't meant to be interpreted the way it now commonly is, because the purpose of the law wasn't included. All you're left with is the same, stupid brute-force that got the law passed in the first place, or maybe the ability to claim that the law oversteps its bounds -- but conveniently, we only spelled out a few areas that laws could not regulate rather than listing the areas that it could. (I know we often claim that we have all freedoms which are not taken away from us, but that doesn't help much when we define only a short list of freedoms we get to keep eternally. Just because our founding fathers lacked imagination shouldn't mean we're now free to take away every other freedom from each other. But we are.)
I would see it as an evolution, a next generation of society to require that all laws include justification, and that failure to prove such justification to still be valid would automatically result in the invalidation of the law. We'd still have a few cooky proofs for selfish laws, of course, but those could be countered in a civil manner, in the open. And we'll hear the cries of those who think that some basic laws ("thou shalt not murder") cannot be proven without the support of religion -- therefore, obviously, this is a bad idea and we should return to ten-commandments-style law ("because God said so.") But think of the increased accountability of our legislature (and ourselves) if every law had to be justified logically; we might even (out of kindness or apathy) allow such justifications to take the form of "because A or B or C" such that any of the three reasons, even by itself, would count as full justification. It's not necessary, of course, but it'd give resourceful and determined people a chance; besides, maybe there are valid cases in which such multi-part lines of reasoning are necessary.
Just think about it a bit. Try to imagine how you'd justify your favorite legislation, or how others might support your least favorite law. Try the shoe, see if it's comfortable. You'd be more accountable, but so would everyone else. As an individual citizen, you could more easily take on bad laws. As an individual citizen, you could more easily pass laws that are good and necessary regardless of how many people would rather you be wrong (but can't prove it.) As a society, you could feel that your laws are more securely enshrined, and that they are true and just -- not mere reflections of passing fads.