You could tell how much he cared about the games Nintendo put out. Sure, he was dedicated to the business aspect of the company, but he also seemed to love games. Where so many directors of other game companies see the games as secondary concern to the business, you could tell Iwata had a passion for the craft.
Tragic. The man while not as obviously big to my gaming life as Miyamoto the fact that his work made EarthBound (arguably my favorite game ever) a reality after falling into development hell makes him important.
Iwata has such an impressive library of games that he's worked on too. The man helped save Earthbound along with HAL labs! Without him, Pokemon Gold and Silver wouldn't have had Kanto! He coded the battle programming for Pokemon Stadium in a week! Other highlights include:
Kirby's Adventure Kirby's Dream Course Super Smash Bros Kirby 64 Super Smash Bros Melee Animal Crossing Super Mario Sunshine Pokemon Ruby and Sapphire Metroid Prime The Legend of Zelda: The Wind Waker Wario Ware Inc Mario and Luigi: Superstar Saga Pikmin 2 Mario Kart DS Nintendogs The Legend of Zelda: Twilight Princess Mother 3 NEW Super Mario Bros Wii Sports Super Mario Galaxy Mario Kart Wii Punch Out!!! Kirby's Return to Dreamland Super Mario 3D Land Xenoblade Chronicles Nintendo Land Fire Emblem: Awakening
Here's a page with a full list of game's he's worked on. Iwata had such an impressive career and he helped to bring joy to millions of people around the world. A lot of us wouldn't be exactly who we are today if it weren't for some of these games. I certainly know they made my life much more enjoyable.