> how inefficient Chinese characters are in general (but especially evident in computing)

We are not in the 90s anymore. UTF-8 has been around for 32 years now. If you’re working for a system that has no UTF-8 support, you have a much bigger problem to worry about.

> characters have no direct relation to phonetics

Most characters are phono-semantic where one part of the character is a phonetic hint and the other is a semantic hint.

> modernize it similar to Hiragana

Hiragana isn’t and wasn’t intended to replace kanji (unless you are from the fringe Kanamozikai). It serves a different grammatical purpose and is complementary to the other two. Kana is useful for an agglutinating language like Japanese, but not Chinese languages.