ES Modules have dynamic imports (https://github.com/tc39/proposal-dynamic-import). The proposal is at stage 4 and is available from Typescript 2.4. We're on version 4 now so I'd expect Deno to have it.

I'm not sure what you mean by "bad practices like include files" so I can't comment on that.

I've found most Javascript developers prefer the await syntax with promises to using callbacks. It gives the code the appearance of being synchronous with the ability to do things more asynchronously if you need. I haven't encountered many who actively prefer the callback style. It gets unruly fairly quickly.

I can't see optional type annotations ever being added to Javascript. They would have to be checked at runtime which isn't something I'd imagine browser vendors wanting to implement.

The feeling that I get is that the standards committee is trying to bring Javascript to be the best dynamic language it can be and if people want more comprehensive guarantees then there are excellent tools like Typescript which give that option.

The fact there have to be multiple implementations of the standard in the various JS runtimes makes it a hard sell to evolve Javascript too far.