You have a good point. If you didn't play MGS1, chances are that you liked Raiden and you probably liked the game a lot. Even the people who beat MGS1 liked MGS2, but not nearly as much because of Raiden, Rose, and the more narrative approach to the game. Plus, Solidus Snake was not nearly as great/memorable of a villain when compared to Liquid Snake or Liquid Ocelot (MGS4).
@Anarchy West- Metal Gear was not included as it was not a Metal Gear Solid game.
the "Solid" part of Metal Gear Solid means the transition to 3D as the series started out 2D, Metal Gear 1 and 2 are still canon although they have been retconned to death they are still canon. Metal Gear 2 is also a favorite among the elite Metal gear saga fans