In fact, to make FSX a combat simulator, you would need extra dll's that FSX.exe would read properly to get any kind of lock and fire at all. If you can get a missile to shoot in the game, you can make it a full blown amazing combat simulator. You just need to know your programming.
You need alot more than that combat sims are immensely complex compared to a flight sim.
Radar Air/Air mode
Radar Air/Ground mode
RWR
damage model
weapons flight model
weapons effect model
ground object damage model
ECM
ESM
ECCM
ground object AI
aircraft AI
missile seeker limits
missile FM
HAVQUICK radio freq
TACAN
LSO AI
CARRIER ATC
AI Logistics support
Aircraft maintenance
Dynamic campaign
IFF
AWACs
AI radar
ATC
Inflight refuelling tanker
Tanker AI
refuelling script for AI jets
MP compatibility and stability
Tanker TACAN
FLIR
LGBs
Buddy Lasing
And thats just a few features that would be required they also require military consultants and constant testing to ensure that it works properly and doesn't break any law or reveal any secret information not allowed to the public. Its not just about dropping bombs or shooting missiles its a whole enviroment in a sim and even the missiles are immensely complex such as the Aim120 which use the launch aircrafts radar(or wingmans radar) until the 120s seeker goes active which can home on jam etc. Dropping bombs can also be quite complex since there are 5 modes of delivery from CCIP, CCRP, LADD, DTOS, manual etc. You've got burst altitude for cluster bombs and arming delay plus fuse selection for nose or tail and other profiles that can also be used. I think for an F-14 addon you can put something in there that touchs on the combat aspect perhaps a Topgun mission pack and use the radar for the F-14 to use a simulated dogfight where the losers aircraft might have smoke released if its hit. The only problem here is the MP side of it as will FSX allow smoke to be released after a simulated guns hit. Missiles would be a problem you can do simulated dogfights with IR missiles but actually launching missiles and having aircraft explode might be tricky for FSX as it ain't really designed for that.