The reason we want typescript to have java-like features is because we work on teams which have decided, outside of our control, that we are going to write our backend in JS/TS simply because it's easier for the bootcamp grads to transition to backend since they already know JS on the frontend. If we wrote our backend in Java, it would require the bootcamp grads to learn a new language, which they're not prepared to do. Choosing typescript or javascript on the backend is not about choosing the right tool for the job (because they are objectively not the right tool for backend development). It is mostly about minimizing the cost of our labor sourcing

As such, RTTI would make typescript go from a compromise language (we use it because we are stuck in the JS ecosystem, not because it's a good tool) to a legitimately useful backend language (We use it because it has the right features for the use-case)

If I could choose what language we use on the backend, I would leave the JS ecosystem entirely and write everything in .Net. But it's difficult to find .Net developers since every bootcamp these days produces react developers