To a great extent it exists because of cultural inertia. The English language has a huge number of inconsistencies as well, especially in spelling; far more inconsistent than, say, Spanish, which is highly phoenetically-consistent. But nobody is editing the English language because their edited version of the langauge wouldn't fly in a formal setting. So even if English or Chinese could be made better, it's not going to happen in a heartbeat. Python2 to Python3 is enough of a pain to deal with maintainence, let alone re-learning a human language.

There are some advantages to Chinese typography over a phoenetic system. Phoenetically written languages like English go from symbols to sounds to meaning. Chinese goes directly from symbols to meaning. Eschewing the sound stage means that as sounds evolve over time, the symbols, whose meanings change on a much slower time scale, are still comprehensible for a long period of time. This means, among other things, that Chinese formal writing is mostly common to all dialects, whereas a pronounciation-based system could only serve a single dialect. For example, in Hong Kong, where Cantonese is the de facto spoken dialect of choice, I, as a Mandarin-only speaker, can still understand all the signage even though I cannot interact with a Cantonese-only speaker. 1000+ year-old texts are reasonably accessible to well-educated high school students.