1. This is not about Putin but the people who died.
2. So you'd have preferred for your (grand)parents to have been raised under a nazi regime over the red army regime? Interesting thought...
This isn't about being uncritically grateful to Stalin, to him personally over other
things that he stood for, it's about the Red Army being absolutely essential to breaking down Hitler's grip over Europe, and therefore breaking Nazi power. The Soviet Union took the brunt of the land fighting in Europe. For three long years (from June 1941 to D-Day) they were the only state that put combat boots on the ground on land
in any substantial numbers in Europe against Hitler, month after month, day and night, along many hundreds of miles, at a tremendous human cost - and that cost wasn't primarily because of their supposedly being inept soldiers or lacking courage and motivation (neither of that was true). The Nazis easily allowed terror methods with Soviet soldiers and civilians of a kind they didn't normally use in the west - gassings, torture and mass shootings of captured soldiers, the killing and burning of entire villages, routine group hangings of men and women in public to strike fear into the people, and so on.
Hitler attacked the Soviet Union, they were arguably his primary target in the war, the war front he really wanted, and over a couple of years they mauled down his war machine. There is no way to defeat a first-rate power like the Third Reich in action without large numbers of boots on the ground, still less if said power has occupied most of a continent right out to its coastlines first, and the Soviets (mostly Russians) did the bulk of that work and made it possible for the invasion in the west (in itself a heroic effort) to be a success.
We all know why the western leaders didn't turn up in Moscow today but I think Dasha is quite right that the memory of the fallen of WW2, soldiers and killed civilians, is getting mixed up with issues of the cold war in a disingenious (or downright mendacious) way by some politicians and media pundits.