Partly because Erdogan's successful destruction of Turkish democracy has grabbed more attention from the world in general and partly because Germans are deeply racist toward Turks...but the second one of those doesn't make Ozil taking pics with him any better.
Nor does it mean that racist Germans don't need to find that same energy for white people who pose with Putin. But the criticism of Ozil that isn't focused on popping off racial slurs is still valid.
No where did Ozil say it was wrong to criticize him. He was speaking to the group of people who did it with racist overtones and who tried to blame him for the failure of the ENTIRE team.