The Dieppe raid isn't forgotten about. The raid is mentioned, sometimes at great length, in most legitimate WWII books and documentaries. Look for yourself, everything from the World at War, to WWII: A Complete History. It is mentioned in countless books as well.

It just doesn't get the same attention as D-day because it was a fraction of the size, and it wasn't successful. It's the same reason why the Norwegian raids aren't given a terrible amount of attention, or the Kasserine Pass.

It plays an important, and I feel over-rated role, in Canadian war history. Canada's war history is strange to me. It is like there's a push to memorialize Vimy Ridge, but not Passchendaele (which was far more strategically important). All Canadian kids know about Vimy, yet if I said "Canada's Hundred Days" I would reckon hardly a soul would know what I'm talking about. Plus, Canada contributed far more in terms of materiale than man power, and Canada's navy and air force played far greater roles in WWII than their army did. It is a strange focus, in my opinion. Not unlike how Aussies tend to stress Gallipoli, even though the majority of the troops were British, not Australian. There's even a "Battle of Australia" day in September, despite the fact that there was no Battle for Austrlaia during WWII and the Japanese never even had the conquest of Australia as a war aim.

So anyways, TL;DR: Dieppe is mentioned, and commonwealth nations I think would be better off if they focused on real roles and important battles as opposed to highly romanticized ones.