Why are bedrock addons so limited?

why is not possible, for example, make custom model blocks since it is supported by minecraft? i play in Pocket Edition and i am making custom model blocks manually and it works when you enable the option "additional modding capabilities". i dont know if it works in other plataforms becouse i dont have them, but you could just unlock the other options and say "it dont work in other plataforms", right?. Please, it is a pain to make everything manually!