The distributions are describing different aspects. Let's take the WoW loot example. A monster could drop 50 different objects with equal probability. Kill it a few million times you'll get a uniform distribution of kills against item type.
Now if we take that same kill data and instead ask how many times do I get item type 2 in 100 kills you'll see a Poisson distribution. If you didn't see a Poisson distribution when asking that question then the events were probably not independent of each other, and hence weren't actually random (e.g. The monster could just drop the 50 items types in order).
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The distributions are describing different aspects. Let's take the WoW loot example. A monster could drop 50 different objects with equal probability. Kill it a few million times you'll get a uniform distribution of kills against item type.
Now if we take that same kill data and instead ask how many times do I get item type 2 in 100 kills you'll see a Poisson distribution. If you didn't see a Poisson distribution when asking that question then the events were probably not independent of each other, and hence weren't actually random (e.g. The monster could just drop the 50 items types in order).