For me Melee did as well as convincing me to get a GC, postponing my PS2 purchase to 2004. Before Melee, almost entire game collection was either Mario or Pokemon, plus Link's Awakening. After getting Melee with a GC in 2002, I asked for and got Starfox Adventures for Christmas, something I wouldn't have probably considered if I haven't seen Fox and Falco in Melee. I can't quite remember, but I'm certain that Melee also convinced me to buy Metroid Prime as well.
Basically, before Melee I was a 9 year old, so called 'casual gamer'. After Melee however, I was still probably what one would call 'casual', but a hardcore Nintendo fan.
EDIT: Also, I would say that if Captain Olimar (or Pikmin in general) made a larger appearance in Melee, rather than just a hard to get trophy, I would've waited until 2006 to play Pikmin.
