Characteristics are the little messages in the summary (like 'Loves to Eat') that say what your highest IV is on a Pokemon.
Natures increase a stat by 10% and decrease another by 10%.
So they're not the same thing, you were wrong there.
People don't like them because they mean nothing practically. You ideally want 31 IVs across the board, so knowing what stat has the highest IV is irrelevant anyway.
http://pokemondb.net/mechanics/natures
http://pokemondb.net/mechanics/hidden
