A cookie fresh from the oven is warm, as well as softer than they'll likely ever be again. For this reason, leaving a cookie on its sheet for the proper amount of time is so important. The extra heat from the pan crisps the outside even further, creating a more firm cookie as a result. The texture is entirely up to the maker and how long the cookie is left to cool on the hot pan.
Behold; I have a cookie that adheres to no rules about texture. Its outside is in unison with its insides; firm to the touch and buttery in flavor. Mais, how can this be? The answer comes from a crime of impatience: not allowing the buttery sticks come to room temp. If, like most of the world, you let your butter sit while you do the dishes, clean the house, maybe go invest in lucrative fiscal outlets, or perhaps mill your own wheat flour out in your personal windmill, you allow your butter to come to room temperature, which is paramount to the formation of the 'ideal' choco chip cookie.
When the batch of cookies was removed from the oven, they looked unsuspectingly normal. Given my experience with making abnormal cookie dough, I have found that the colder the margarine is, the more similar the result is to adding too much flour or beating the mixture for too long. It seems, without any actual research done on the matter, that the cookie becomes super-saturated with flour, creating a stiff batter that leaves some flour at the bottom of the bowl and out of the party. No big deal as the cookie dough is still amazing and safe to eat (no eggs = no salmonella scare) so if the cookie fails, the dough never ceases to satisfy. I pay the stiff dough no mind, as I've learned it's a simple sign of my eagerness to consume the dough rather than get the dough on cookie sheets to bake, anyway. Viva impatience.
So, see? The chocolate chip cookie was birthed of a simple kitchen error. If the result pleases you, there is no error made. Just kitchen wizardry.