Huh? It's very easy to input Han Characters on modern systems. Most people type it a phonetic alphabet (eg, romanizations like Hanyu Pinyin, or indigenous phonetic alphabets like Zhuyin) and a little program pops up, giving you a list of matching characters, and you select them. Googles ones are very good (they even know regional varions in mandarin pronunciation).

It's entirely conceivable for a programming language to be made with Han Characters - because it's a solved problem to input Han Characters on keyboards.

Or Have I missed the point of what you wrote entirely?