1) I only mentioned that it wasn't a bad game because I didn't want people jumping on me for criticizing the game so badly. the game itself is quite genius in that it's simple but can do so much.
2) They have added things to the game but how much has that changed the base gameplay? Almost not at all. Pokemon is still part glorified paper/scissor/rock, part cock fight, part collecting game. Things like new ways of finding Pokemon, natures, abilities, berries, and all that hasn't changed the gameplay. It is still you find Pokemon. You raise Pokemon. You battle Pokemon. Don't take offense to this, one of the things that makes Pokemon so great is that it's so simple but can do so much.
3) I know you can sit there and rattle off things added to the game but you can do that with any game on that list. In Zelda they've changed the art style, completely different story and theme. The Virtua Fighter has added new fighters. Street Fighter...well maybe you can't say that with SF games. The point is the core gameplay hasn't changed in those 10 years.
4) Tetris new games modes, by definition, change the core gameplay. You still have classic Tetris but you also have sticky, puzzle, stack, the one with the ball, 3D Tetris, and many more game modes. All of those change the core gameplay.
