Unique characters being required to distinguish homophones in modern written Mandarin is mostly a circular effect due to the characters already being available, so people use them in ways that would be ambiguous when read aloud (as intentional puns or simply to be more concise.)
If there had been no preexisting writing system and written Mandarin was a simple transcription of spoken Mandarin, introducing characters would be about as helpful as indicating the Indo-European roots of words in English writing, which is to say that some people might get a feeling of epiphany after realizing the connection between seemingly disparate words, but it would hardly be practical for everyday use.