Sure you could -- and eat up all your framerates at the same time.

Think about the F/A-18 sim: you had ONE flyable aircraft, with (I'm guessing) a limited area of flight and very few (if any) cities.  The AI were most likely very simple (no interior parts, etc) and the sim was GEARED precisely for running those very specific gauges and devices.

Now think about the FS structure: multiple flyable aircraft, with enhancements ranging from simple AI aircraft all the way up to full-immersion cockpit capability.  An entire world fully modeled, with thousands of airports and hundreds of modeled cities.  The sim has to be geared to accept multiple types of interfaces, from steam-gauges to PFD/MFD structures.  This inhibits the speed these systems can function at, and the ability of the sim to render them quickly.

You are by no means not going to find this for FSX either now or sometime in the near future, but you will be paying a pretty price for it, and you better have one heck of a machine to match.