Why neither Arabic or Hebrew didn't accept vowels as the core of its script?
[0] In case you are not familiar: https://en.wikipedia.org/wiki/Semitic_root#Triconsonantal_ro...
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.