It's not a universal. Before World War II, the Soviets used functional designations for their aircraft also: R for recon, U for trainer, I for fighter, B for bomber. Soviets never used designer names for tanks--those were always functional, like BT (fast tank), just T (tank), or named for somebody famous (KV for Kliment Voroshilov).

I think it makes a little more sense when you realize that the initials don't stand exclusively for individual designers as much as for design bureaus. That is, it's about institutions as much as it is individuals, though the Soviets did pay attention to individuals as well. That's why Sukhoi aircraft still come out even though Sukhoi's been dead since 1975.

The US Navy actually has a history of including manufacturers in designations. Before the 1962 unification of aircraft designations, the Navy used a system in which the numbers were sequential for each manufacturer. So the F3B was a biplane from Boeing, and the F3D was a jet fighter from Douglas. They still use a similar scheme for the nuclear powerplants on ships and submarines.

Your basic premise is flawed, I'm afraid. The Soviet/Russian planes are not giving credit to their designers, but to the companies that produced them, which are named after their chief designers.

A MiG-15 is not giving a nod to Artem Mikoyan and Mikhail Gurevich, but to the Soviet Design Bureau "Mikoyan-and-Gurevich." This is much the same as saying the "Douglas Dauntless" or "North American P-51 Mustang" or "Lockheed Lightning."

Along with that, the American numerical designations have nothing to do with their manufacturers. The F-86 Sabre was built by North American Aviation, the B-52 by Boeing, and so forth. The use of "F," "B" or "A" is simply to designate mission roles, something that carried over from World War II (though "F" for fighter replaced "P" for "pursuit").

It's just shorthand to call a plane the F-15. The full name would be "McDonnell Douglas F-15".