Because we actually, you know, have faith in Sakurai to deliver decent movesets. He's done so for even the most unlikely of characters and characters with no moveset to take inspiration from (see: Captain Falcon), so we don't take much stock in the quality of fan-made movesets - since we know that regardless of the quality of said movesets, Sakurai's one will be a good one.
To put it simply, "moveset potential" is not and has never been a remotely plausible argument for or against a character. Sure, it helps - but Sakurai's criteria for decent moveset potential is nebulous and immeasurable, considering characters like Wii Fit Trainer.
Oh, and movesets are really something you have to see in action to judge. If somebody posted Wii Fit Trainers moveset three months ago, they'd get run out of town so fast they'd never come back.