It doesn’t have on-board look-down-shoot-down or IR track-and-lock. Such can be added with a pod but there are tradeoffs, such as reduced range and performance and the fact that the pod isn’t going to be as good as a system integrated into the airframe. Unfortunately, literally every other competing fighter out there has this and the F-15 has a great big IR signature.
As a gun fighter, the F-15 has been surpassed by thrust-vectoring fighters.
When I flew the F-15E we did have look-down missile capability. . .for decades.
Thrust vectoring makes for a nice airshow but if you use it, you become a target.
Oh, and there is no “notch” with the F-15C or F-15E radar.
With the Lantern Pod, you can locate a thermal target and then slave the radar to the heat source, and there are missiles that do not need to go HPRF before launch, or even have a lock of any type.
Other pods can be internal with no real negative impact on range or maneuvering capability. IR is a concern if you are talking about the merge, not engagements at range.
Closing to the merge and then using thrust vectoring is something to avoid. Why? Because if you close to the merge and use thrust vectoring this means you lose your speed (”speed is life”), and become a strafe target.