Recently, it seems like in the animation industry drawing rough has become a style in it of itself.. and nothing else! There is the mantra "It's better to draw rough and make it clear then to worry about the details".. or.. "block in the general ideas first..then the details are secondary".. But here is another perspective from a great draftsman Rico Lebrun (famous fine artist and teacher at chouinard and disney)
"Even the slightest indication must at all costs avoid vagueness. The writing must be intense and specific. The blocking in of large mass, simulating boldness, is often a promissory note which we will not be able to honor later. It is, in fact, the story of the particular will lead properly to the general. A false reading of the particular will change the entire structure"..
here is Lebrun on sketching..
"..When we cannot really talk we gossip. When we cannot draw we "sketch" hoping to bypass the difficult through brevity.. the sketch should be the unering chart of a condition. It should never be used temporarily to placate vanity, which seeks to affirm itself through the delusion of promises made and promptly forgotten. Anxiety can encourage vacillation to suggest promising but untenable hints. It can lead you to shoot a round of ammunition at an imaginary target while the enemy is sitting on your rudder. It can reassure for the wrong reasons.."