I'd prefer to make name hashing opt-in for now until we get bigger pool of testers. I'm planning to write a blog post on Typesafe engineering blog about name hashing with results of my benchmarks showing that in many cases it brings big improvements. I also plan to include information on how to enable it in sbt projects, Play projects and IDE. This should be enough of buzz to make a lot of people give it a try.

There's another argument for making it not enabled by default: sbt 0.13.x won't have it enabled by default and IDE tried to stay as close to sbt as possible so far.