At some point you earn your poet's license. Dylan Thomas and, oh my, James Joyce are good examples. Until that time it's in the common interest if we lesser mortals observe the conventions, such as they are.
I strongly disagree. Creative writers, as artists, have every right to experiement with their work in language and form as they see fit, no matter at what level of stature or accomplishment they are perceived to be, just as every painter has the artistic freedom to experiment with the stroke of the brush. Whether it works or not is up to the audience and the critics. Writers like Dylan Thomas, Eugene Ionesco, e.e. cummings, Ray Bradbury, William Faulkner (he of the 5 page sentences) did not suddenly leap to a new style in the mid-course of their careers just because they'd achieved some stature, that was always their style. In fact, they got noticed because they dared to be different. The notion that someone should somehow deem to sanction literary artists the 'right' to experimentation at some point in their careers is just absurd.