It's the difference between starting out to invent to spec in 2001, and finding >10 years later that Big Tech is doing all the work for you. Phones in 2001 didn't have inertial reference systems.
Also, the JSF spec insisted on IR, which meant off-helmet sensors. The low-light capability of small CCDs has come a long way since then. And I believe Stryker is designed to work with a HUD, not as a substitute for HUD, so the extreme-assured-accuracy requirements can be left to something that's bolted to the airplane.
PS Did they call it Stryker because we can all count on it?