Maintenance nightmare. And that matters, a lot. Every hour it's being repaired is an hour it can't be used. Maintenance crews cost money, take time to train, are hard to recruit, need space (particular problem on ships). The fewer you need, the better. Also, the F-14s aren't really "here now". They were wearing out, & would have to be retired or refurbished soon. Almost certainly cheaper to buy more F-18E/F than keep the F-14s flying. Just retiring the F-14s & switching the crews to F-18 maintenance might have given more aircraft ready for use.It still urks me that when we're having to produce 300 million dollar aircraft that we couldn't keep up something like the Tomcat who's power and weapons are still effective and most importantly they're here now. Hutch
Even if an aircraft doesn't fly, it deteriorates. The USAF is now having problems with the wiring on F-15s shorting because insulation is falling off. Deteriorated with age. Repairing it is a nightmare. Parts go out of production. The factories which made parts cease to exist. New parts mean redesign, retest, re-certificate. Some of this stuff was never meant to be replaced, because it was expected the aircraft would be scrapped before that was needed, so doing so means dismantling the aircraft. There comes a point where it's quicker, easier, & cheaper to give up & buy new.