It's most likely a cost thing, aimed at the more performance-minded vehicles Subaru has:
Also, the new Forester is going to have a DIT model as well, so Subaru does have direct injection models, albeit for turbo versions
Originally Posted by Zeeper
Probably not anytime soon. They are still working out the direct injection with the new BRZ and the next generation WRX/STI is under development.
The Impreza model is already 'new', and Direct Injection was done in conjunction with Toyota, the clue will be if the new WRX/STI uses direct injection. If not, don't count on any other models getting it soon.
See the Legacy DIT and the soon-to-be released Forester XT with DIT, and I believe these are Subaru's own DI systems, not Toyota's