Fizz' ult change didn't accomplish its intended goal
Riot was unhappy that players would sit on top of targets and ult them at blank range. They changed his ult with the intention of fitting a very characteristic component of assassin gameplay: high risk - high reward. Players had to trade the shorter, easier-to-land skillshot for less damage, or risk the longer, harder-to-land skillshot for more damage + a bigger knockup.
Why then has riot made the hitbox of the skillshot scale with its length? His ult is almost as easy to hit at long range as it is to hit close range. Players never opt for the shorter option, because the trade is simply not worth it.