I'm not sure what's going on here. We started out with a misspell of longueur, which resulted in a paucity of search hits and a questioning of the definition. (longueur gets 812,000 on the google-ometer.) Now we're questioning the etymological leap from 'length' to 'excessive length'?

Perhaps we should take a look at AHD4: French, from Old French longor, a protracted discussion, from long, long, from Latin longus.
That's it! We can blame it on the French..