BackFire
Blood. It's nature's lube
Don't know if anyone has read this, but it's a section of the Gamespot review that compared both the GC and the PS2 version....
"If you're already familiar with Resident Evil 4, chances are you just want to know how the PS2 version stacks up to the original. The good news is it stacks up remarkably well, resulting in one of the best-looking, most atmospheric PS2 games to date. Having played the original, you'd find no signs that the PS2 got the short end of the stick, even though this version was announced only at about the same time as production on the original was wrapping up. The game controls just as well on the PS2 as it does on the GameCube, and it boasts support for Pro Logic II-equipped sound systems and widescreen high-definition displays (and this is true widescreen support, whereas the GameCube game is letterboxed even if you play it on a widescreen TV).
The content of the GameCube version is all intact here, but in addition to that, some key extras have been added. Chiefly among them is a side story called Separate Ways, which lets you play as the elegant, enigmatic spy Ada Wong as she finds herself in the same place at the same time as Leon, the hero of the story. In addition to featuring some slick new cutscenes and more than a few more hours of great gameplay, Separate Ways sheds new light onto some aspects of the storyline and explains why some of the things that happen to Leon are more than just happy coincidences. The difficulty in Separate Ways picks up at about where Resident Evil 4 leaves off, so Ada will have a tough fight ahead of her and will likely need to avoid as many enemies as she has to kill. As such, the feel of the action in this episode is different from the parts of Resident Evil 4 during which it takes place, even though Ada plays pretty much the same as Leon (though she's a little faster and gets to use a cool grapple gun). Overall, Separate Ways is a well produced and exciting bonus.
A few additional weapons and unlockable costumes are also new to this version, but it's not necessarily worth getting a second copy of Resident Evil 4 just for this extra content, especially since none of it is available up front. Besides, while Resident Evil 4 looks incredible on the PS2, it doesn't look quite as good as on the GameCube, where it has richer colors, sharper-looking environments, and nicer lighting effects. Larger foes also look better on the GameCube (while smaller foes melt away faster when killed), and the earlier version's loading times are also shorter. Pauses during the interactive cutscenes are also longer by an instant on the PS2, making the interactivity feel a bit less seamless. So, since the underlying gameplay is exactly the same, the slightly but noticeably better-looking GameCube original ultimately still has the edge. That about covers the differences how Resident Evil 4 compares between the PS2 and GameCube, but if you're unfamiliar with what makes the game itself so good, keep going."
Yes, but my question (so far dodged) has been "Why do people believe it will make the game better?". Because some people do believe the GAME is a better game, rather than the GC game with add ons.
3 words, my friend - More is better - Too many people, this is true. You get the same game that was on the GC, with slightly worse graphics, plus you get some fun little extras. To some, that makes the game as a whole better, if you include the extra features. Though it makes no difference to the main game itself.