Probably cost as the number one factor along with all of the money used to buy them heading off to the USA. At least some if the money used to develop and buy the ADV stayed in the UK. It would also have made the RN FAA a bit jealous to have the worlds best naval interceptor in RAF service! It would have been interesting to see what the Brits did with the F-14 since the TF30s we're not up to the job. Scaled up RB199s?