Codegen and Substrate types

[MOZGIII]

Why doesn't codegen take care of generating chain-specific API types for Substrate chains?

To be specific, I mean this (package.json > scripts):

    "defs": "node node_modules/.bin/polkadot-types-from-defs --endpoint ./metadata.json --input ./src/interfaces --package interfaces",
    "meta": "node node_modules/.bin/polkadot-types-from-chain --endpoint ./metadata.json --output ./src/interfaces --package interfaces",