There's ONE argument that I'm partial to:

if you get the static type system wrong once, there's no going back

Take for example, Rust: mut, Send, Copy, Drop, Debug, dyn have all their warts because they are special and you can't fix them because you'll break previous code.

In a gradual typing language you could potentially bolt-on your own type system as a package where it just runs the type checker if you want one. It just so happens people who favor these gradual typing systems don't do a good job of creating those typing systems because they are not that into types in the first place.

But in theory, this kind of a system would let you not worry about types when prototyping the system, then put some bounds later based on your requirements.