Tetris was not made in the last 20 years. Though I still don't quite agree that OoT is the only masterpiece in the last 20 years. I do however agree that it IS a masterpiece(even by today's standards); therefore, no I don't think it is overrated.
The definitive version of Tetris, the original Gameboy version came out in 1989, which is the version that people consider the true masterpiece. It's just hard for me to show that since all of the Tetris games back in the days had no subnames. They were all called Tetris.