The Eurofighter, as you say, came out to late to actually be used extensively. Everyone wants US fighters not European built fighters, why? Because we have the best..............
The point of having the minimum of 300 is to be able to adequately protect the US while fighting two major wars. The fact of the matter is that we must replace the F-15 fleet and the F-16 fleet. It is one thing to have a bomber, such as the B-52 in service for over 30 years, but a fighter has to stand up to more g's for longer periods of time, and more often. The airframes are beginning to show this. Plus in war we don't want to lose anyone, or even chance losing anyone(it happens, but we want to reduce the amount as much as possible). Along with that, Russia is planning to build a newer fighter. Called the Sukhoi T-50 or PAK FA. Whether the aircraft will come out to compete with the F-22 as it was designed to do or not, we must be prepared simple as that. In reality that is why we should have AT LEAST 300 F-22s. To be prepared for everything and anything that comes our way.
Why should the F-22 take over the F-15E role if those aircraft are still viable and will be for another 20 years.
The F-35 is not my favorite aircraft. I've never been a fan of single engined aircraft of the modern era. They end up ugly and are MRF's which really annoy me. Specialty aircraft get the job done much better, but its all about money.................
You're just talking about having a smaller amount of explosives that pack a bigger punch. In other words, HE or fuel-to-air bombs..................but smaller and newer..............
I really, at this point, don't see any need to improve the weapons we use to the extent that you are talking about, we need to focus on the delivery systems first.............