[pcwalton]

Developing a standard for Rust would have incredibly few practical consequences, given that there are no alternative implementations. It would, however, consume a lot of people's time. That time could be spent on things with practical impact, such as compilation speed improvements, stabilization of features, and better optimization.

The reason why Rust was stabilized in advance of a standard is that stabilization had an immediate practical consequence: ceasing to break code. A standard, by contrast, would have virtually no practical use.