Why do we remember Shadow of the Colossus?

This article contains spoilers for Shadow of the Colossus.

What if there was a game that told its story through subtle changes in the character?

What if there was a game that pushed hardware to the limits and became something ahead of its time?

What if there was a game so pure and complete in its vision that the final product resembles test footage made before production had started?

What if that game came out in 2005?