Uh.. what?! They clearly developed Figment to be popular and unique to said park & one that was a catalyst to a ride about the real world concept of Imagination. What I think you meant was “accidental” was not creating & marketing more characters like him to begin with…
Now if we can talk about any “mistakes” here.. it’d be the moment they thought shoehorning & advertising film IP into that pavilion via Honey I Shrunk the Audience (as the main attraction, I might add..) & treating free spirited creativity & Figment like they were a nuisance or a problem for putting that lousy IP retheme idea on blast (rightfully so, I might add) was a good idea. Now ‘that’ had a big impact on the the ride & rest of the desecration of EPCOT for the past couple decades or so…