80% of the value of TypeScript is that it will tell you when when you changed or added a parameter and forgot to update it everywhere, you doofus. The other 20% is that it keeps coding agents from going too far off the rails. Trying to use the type system as a metaprogramming language is only valuable as a fun exercise, but of negative value in real world projects.
That's a little ungenerous. Richer types are not intrinsically about metaprogramming, they just let you model your domain more accurately so you can turn runtime errors into build-time errors. If your system already has natural constraints, you get to document them in a machine-checkable way.
