It's not like 1.0 represents all the features they want though, there are many language and library features that are planned for the future.
As an example, the IO subsystem had lots of generality designed for when lightweight tasks were still a feature. By ripping them out, the library is both easier to use, and simpler for future expansion. It was also changed to support the general error-handling facilities that Rust now has (which are partly similar to the old IO-specific error handling features, but wouldn't work well with other libraries).
Others like the collection-api cleanup were badly needed, because of inconsistency and a lack of direction over time. Now the collection-api is much cleaner, and consistent between different types of collections. This allows them to add things like collection-api traits in the future, and newer collections that can follow the same api conventions
The majority of software can be written in python, Go, Ruby, Haskell etc. but the software that need to be native is extremely important. Improving browser parser by 10% improves millions of apps. Having better and more productive language is better for faster innovation.
My only problem with Rust is that the first version has a lot of features. The should have shipped 80% of them and add the rest in 2.0.