G'day Ray,
Society has a long history of the term "common sense" being interpreted by those who don't have it. "Ignore all rules" strikes me as more pro-active than "Use common sense." A person who invokes it cannot do so effectively unless he knows what rule he is ignoring, and needs to be able to substantiate his stand with something more than infantile ignorance.
You need to know the rules so you know what you're breaking.
Consequently, the rules aren't there to say "you must always follow these rules". They're there to encourage people to think before breaking them.
There is nothing wrong with a chap breaking the rules if he has a good reason (on Wikipedia, defined as "to benefit the encyclopaedia"). When we confront rule-breakers (e.g. vandals), the problem, despite popular belief, is not that they're breaking rules in the first place, but because in doing so they're harming the encyclopaedia. They aren't trying to benefit the encyclopaedia.
It's a short leap from there to ignoring all rules altogether, except as a handy reference guide for people who are new and unclueful[0]. If I enforce the rules to the benefit of the encyclopaedia, then I am doing the Right Thing. Rules lawyers would agree, but what they miss is that the important thing is the benefit, not the rule. If I enforce the rules to the detriment of the encyclopeadia, then I am doing the Wrong Thing, as the important thing is the detriment, not the rule.
Moving from there, it's important to strive to do the Right Thing, and not the Wrong Thing. Knowledge of what this is only comes with experience on Wikipedia, and a willingness to expose one's self to Clue. Even then, though, there are things on which a clueful person will be unclear. In such cases, one makes reference to the rules and to the advice of more knowledgeable persons.
Ignoring all rules is not making it up as one goes along. It's knowing what the Right Thing and the Wrong Thing are, and acting appropriately. When you lack this knowledge, you don't ignore the rules, because you don't have a good reason for breaking them.
[0] Contrast "clueless", which has an element of wilfulness, that the person has deliberately evaded cluefulness, with unclueful, which we can take to mean that the person simply hasn't attained Clue yet.