In both cases the idea was to start simple in wasm 1.0 and leave those things for later. Both are being discussed now.

For the first see e.g. https://github.com/WebAssembly/design/issues/1397

For the second, WASI is doing that on the server, while on the Web we just haven't found a way that is better/faster than calling through JavaScript (we tried to do direct WebIDL bindings among other things).