[CraftThatBlock]

A big issue I see with this is that having custom classes (the whole extensibility point), at least in TypeScript (without re-declaring them).

[qudat]

I investigated figuring this part out. Theoretically you could build a postcss plugin that generates the proper typescript types. It would be difficult.

[franciscop]

If typescript is an issue don't use it ;)

[jeswin]

Giving up the myriad benefits of type-safe code over this relatively minor and entirely subjective coding style preference will be a poor engineering decision.