The long-and-short of it is: because that's how it works, and it sets the precedent that other ED modules should follow a similar level of quality/simulation. Primarily, the Hornet has been in development far longer, and yet its INS/GPS is not as detailed as this yet, having been plagued with middling problems (for quite some time) literally requiring the use of GPS and other workarounds for it to be combat-effective.