I would think that they took out the multiplay because it stunk. This type of game just doesn't make for a good multi-game.
A good multigame has to be fast paced and stratigic. Indy doesn't start, stop, turn or jump fast enough to make the game multiplay. It's a very realistic game, which is perfect for an adventure game, but makes for an absolutely horrible multiplayer game.
Unless the point of the game was to see which of your friends could solve the puzzle the fastest it just wouldn't make sense. Imagine 8 Indy's running around having a deathmatch.
They most likely left it out instead of getting complaints about it later.