The important thing the Russians realized, early, was that air space has to be patrolled by shoot-no-shoot decision-makers aloft. Robots and teleoperated systems are not very good at that kind of discrimination. We in the West, often scoff at Soviet era pilots, thinking they were just there to fly basic maneuvers as told to them by their ground controllers. Not so. Real Russian aerial tactics, such as the hammer and anvil, relied on ground controllers to big picture the situation and paint it for their pilots, but Russian flight leaders took that information and used it in the air to engage adversaries with the appropriate set piece, much as we did when we finally worked the kinks out of AWACs air battle direction. They also realized that once the situation developed, it was man/machine against man/machine. It is not too hard to see a lot of functional similarities in how the F-4 is handled and the Mig 23.
Just as we moved past the fighter wall, once we figured out the furball was inevitable, so the Russians evolved past it. Mig 29 and Sukhoi 27 can be seen as natural evolutions and extensions of Russian air combat practice and not as mere reactions to the Falcon and the Eagle. IOW, don't be blinkered by certain myths or assumptions. The Mig 23 is as part of a natural evolution of Russian jet powered air combat as the Phantom is to ours. Just a phase that anyone with good tech and good tactics passes through to the next phase beyond. That is why we call them aircraft generations. You cannot get away from a certain kind of "standardization" on how to employ technology because the way we humans are evolved, kind of dictates that our technology has to be user friendly.
So if a Sukhoi Flanker and a Boeing Eagle look similar, it is not because someone copied someone else, or the Eurofighter Typhoon and the Rafale would be cited as England copying France or the other away around, it is because in that generation, different tech trees paralleled the same "superficial looking" solutions.
We should be looking with great curiosity at the F-35 and its contemporaries. I'm seeing quite a split as various different national tech trees come up with curious functional airframe differences that are strikingly dissimilar.
Just saying; respect the effort and genius. Nobody who bends aluminum and produces a viable fighter platform system complete with supporting systems, and then trains a pilot well to use that entire system of systems is to be disrespected ever. I sure as hello will not.