don’t know where you got the impression that the F-15E can’t take care of itself air-to-air.
your words even speak to that ...You say it can “take care of itself”....correct ...it can defend itself ... that’s its mission get in attack ground targets and get out without being shot down... in air to air ...it’s always a defensive mission for it...it’s not an aggressor in aerial combat
F35 need to be able to defend itself against fighter out to shoot them down.... The F35 not going to be defending itself against other ground attack aircraft that can defend itself ..like an F15e
The difference is between an aircraft assigned to be on the offense against other aircraft in the air versus aircraft on defense in the air...
The F15e is carrying a lot of things that are virtually no use in the offensive air-to-air combat mission... it’s not an air superiority aircraft... it’s a ground attack aircraft that can defend itself and you don’t use it to attack other ground-attack aircraft.. and you sure as hell wouldn’t use an F15e to attack air superiority fighters...
In fact, a Clean F-15E is lighter, has more powerful engines and can sustain a higher turning G load than an F-15C. It carries the same A-A armament as an F-15C. The only real difference besides the second seat, is that the F-15E has permanently attached conformal fuel tanks and can carry more external ordnance.
Arguably, that second set of eyeballs is a great asset in A-A combat. I would sure as hell consider using it as an air superiority fighter if the mission demanded that.