I never really understood the reasons behind the replacement and upgrade of military aircraft until recently, mainly thanks to the horrible whining noises made by opponents to the work.
Seriously, many of these noisy objects have no idea what they are talking about, and qualify for the "Empty vessels make most noise" award.
I used to think they were all just 'fighter jets', maybe with some specialisation, such as 'interceptors' for example.
But thanks to the various battles between opposing groups regarding such aircraft I have become much better educated about these aircraft over the years, understand the problems about replacing them, and how even two such aircraft that may look superficially identical can be designed and equipped to serve different roles, and that one can be utterly and completely useless in the role of the other.
I'll miss the variable-sweep or swing-wing of the Tornado.
But seeing the design/manufacture hurdles it brings, and the complexities of manufacture, it's small wonder the mode is no longer supported. But it also taught me a lot, and is one reason I often laugh at some flight and design ideas some folk come up with for variable geometry aircraft. Seeing what the military had to do to make this work... well, I'd expect most of the civilian efforts to fall apart rapidly in service (if anyone ever backed them).