Because these scripts were developed while societies transitioned from oral tradition to literacy. It's only modern literate language that brings with it an aura of exactitude. Oral tradition allows for more ambiguity and alternate interpretation, and arabic and hebrew developed in a way that suppored that expectation of flexibility and ambiguity through a triple of consonants having many possible meanings.
And? Castillian Spanish can be traced to vulgar Latin (almost) and then to Latin, yet we did
changes on usability, grammar and spelling over centuries.
Being Arabic and Hebrew "inmutable" on vowels hinders the main reason for a language to exist, its main purpose: being able to be a proper tool to send a message between two or more peers.
There's no excuse to put vowels if you already set an standard, as the RAE did for Spanish five centuries ago.
> its main purpose: being able to be a proper tool to send a message between two or more peers.
You're projecting modernity back in time. The old purpose of writing things down was as an aid to memory, so you didn't need to record everything, just enough to jog your memory.
