Surely an explicitly tonal alphabet is preferable to a language with implicit tone (e.g. English). I can only imagine that learning English's implicit tone curves pose a challenge to speakers of Asian languages.

(Esperanto is intended to be perfectly understandable without tonal inflection, through the use of particles such as "ĉu" and "ja", though in practice Westerners universally tonally inflect their speech because they don't know otherwise.)