There are lots of rules that govern the mechanics of writing. So many that we have editors to keep track of them and go over our writing to make sure we don’t embarrass ourselves by committing some super writing faux pas.
Some writers make it more challenging than others by insisting on breaking the rules on purpose. e.e. cummings is a prime example. He eschewed capitalization and got away with it because it was his style and he was a great poet. My brother likes to eschew capitalization also. I think his eschew-ment is a bit more suspect, however. In his case, eliminating capitalization probably has more to do with not wanting to take the time to push the shift key to turn the letter from lower case to upper case.
When writing, the rules you choose to enforce or ignore must always enhance communication. Here’s the rule I go by when breaking the rules: If you break the rules, be consistent in your application of the broken rule. That way, the reader, once he/she deciphers your unusual punctuation or grammar usage, will learn to apply the broken rule, compensate for it and understand what you are communicating.