I don't think pinyin was even meant to represent voicing and aspiration in a way that is similar to English or otehr Germanic languages. There are many other languages using Latin alphabet which are a little bit different with both consonants and vowels, and that doesn't stop from sharing the letters.

Pinyin does a good job in providing a fairly consistent way to present Chinese sounds using Latin alphabet. It's also the workable way to input Chinese characters on a computer keyboard. It works, it is consistent, and it is now ubiquitous in China.