English is one of the most contradictory and strangest languages in existence in terms of grammar. Quite often the rules do not make sense because it has been garnered from several sources over the years and in a way that was actually illogical because the original scholars who compiled the rules in the 17th century made certain assumptions. The main one they made was that English was a Latinate/Romantic language when really it is a Latinate/Germanic hybrid being derived from both Anglo-saxon and Norman French roots. An example of this is the use of the words Pig and Pork and Cow and Beef to describe the animal and the food that comes from it.

This why the rules of English grammar often do not make sense when compared to other languages. It is also why it is easy to break said laws without knowing it.

A good reference (certainly for punctuation abuse) is Lynn Truss's 'Eats, shoots and leaves' which is a fun and irreverent look at grammar abuse for pedants.

You can also often get away with breaking the laws when the aesthetics of a written work are affected by it. The classic example of this is the Star Trek 'to boldly go' rather than the correct 'to go boldly'. The latter is grammatically correct whereas the former has a greater poetic quality. I am not sure whether being published gives you the right to break the rules but more having the confidence to be able to apply the poetic license laws correctly and be able to tell an editor this without them eating you alive (bearing in mind that good editors are usually horrible, nasty pedants who get a kick out of making you suffer ).