I have no way of knowing how deep your knowledge runs, but caring for ANY sword is a 'given', regardless of its era. They should ALL be cared for and passed on in as good as or better condition than you received it. There is nothing wrong with polishing blades, as long as you know what you are doing and don't take your efforts too far. Obviously, you need some education in this area beforehand, but cleaning up marred or badly messed up blades with the appropriate stones is a source of deep satisfaction.
Although blades made for WW2 are looked down on and not collected in Japan, they are occasionally surprising in their quality and usefulness. Not all were just punched out for average service men; many were made for officers by better-quality smiths, and are nice pieces of work. There is no 'holy grail' about remounting military swords. As a matter of fact, once remounted in older, more 'traditional' furniture, they often make very decent Iaito or practice swords for tameshigiri/test cutting.
That said, the main reason I write this is to make you aware of a very good recent book in English that deals almost exclusively with modern blades, beginning with WW2 ... "Modern Japanese Swords and Swordsmiths" by Leon & Hiroko Kapp, and Yoshindo Yoshihara (who also collaborated on a very nice book some years ago, "The Craft of the Japanese Sword). An outstanding and informative book, it goes on to outline many modern smiths working in Japan. Consider finding this book and you will be pleased with the knowledge and insights you will have gained.
Good luck. David Terrell