I totally agree with you. The three piano concerti are no weaker than the standard Russian romantic concerti. My favourite Medtner:Night Wind SonataSonata ReminiscenzaSonata Tragica (with Canzona matinata, of course)
Did you intend to phrase it the way you did? It sounds as if you consider all Russian concerti weak. And if that were true, I just might have to kill you.