When I think of boilerplate I think of context that is made explicit. Things like type annotations, longer variable names, the lifetime or attributes of some class or data etc. These things are extremely helpful for a number of things - they convey context from writer to readers, they aid in proving the code correct, and they can make code faster.

The context almost always exists in the writers head. We all have a specification of our program based on our expectations, and we type out code to turn that model into an implementation. We only spend so much time conveying that model though - most of us don't write formal proofs, but many of us will write out type annotations or doc comments.

The cost is usually as simple as expressing and typing out the model in our head as code. Languages that are famous for boilerplate, like Java, enforce this - and it makes writing Java slower, but can also make Java code quite explicit (I'm sure someone will respond talking about confusing Java code, that's not the point).

Reducing the cost of conveying context from writer to reader means we can convey more of that context in more places. That's a huge win, in my opinion, because I've personally found that so much implicit context gets lost over time, but it can be hard to always take the time to convey it.

Think about how many programs you've read with single character variable names, or no type annotations, or no comments. The more of that we can fix, the better, imo.

Tools like this do that. TabNine autocompletes full method type signatures for me in rust, meaning that the cost of actually writing out the types is gone. That's one less cost to pay for having clearer, faster code.