The RAR format was chosen for the new extraction formats because:
It has better performance (works faster, has a lower processing cost)
- It creates more compact archives for this lesser cost (even just a 10% reduction is a very important difference when you consider the Gigabytes extracted for your account)
- It has better / more universal command-line support (the freely available versions of the RAR software support command-line extractions on all operating, which is not the case for ZIPs)
Using “unrar” to extract these archives is really just a matter of downloading the unrar package on linux or winrar on windows and changing the command line used to extract it.