I'd argue it's placement, along with other "odd" placements in the game is indicative of KH 1's tendency to encourage exploration. It's actually pretty clever when you think about it.
The first keychain you're guaranteed to get is the Jungle King, which (canonically) is the first one Sora ever receives despite visiting Wonderland first. Eventually they'll reach the second set of worlds and receive the respective keychains from Agrabah, Monstro, Halloween Town, Atlantica and Neverland. By this point, smart players will wonder why they haven't received a keychain for wonderland or olympus, and if they are persistent, they'll be rewarded for their efforts with Lady Luck and Olympia, among the other keychains awarded through the colliseum and exploration of Hollow Bastion.
(Plus, Lady Luck is pretty overpowered as is, +2 magic in KH 1 is nothing to sneeze at).