It has a been a while since I've played Shadow of the Colossus. Some older games age extremely well and some do not, especially when you are talking about game play. My guess is that SotC is one of those games that doesn't age well. At the time it released, the appeal was that all of the monsters were just so friggin huge. But since then there have been games like Dark Souls that do the giant boss monster a whole lot better.
SotC is what I would call a groundbreaking game. It's important because it has influenced several great games that came after it. But when the later games do the same thing, but better, then that makes the earlier game not age as well.