While they did ‘add’ damage, Yi’s W is worse off
In the recent patch, Riot decided to tweak Master Yi’s W ability, Meditate. They did so by reducing it’s cooldown dramatically, allowing him to sustain in the jungle slightly better. However, they reduced his healing on the W every tick across the full channel time, meaning a huge reducing in healing overall.
While Riot attempted to rebalance Yi as he wasn’t in a good spot by adding damage to his W, where a full channel would grant him extra auto damage on the next 3 auto attacks, it isn’t that good in team fights. In a team fight, Yi will almost never meditate for his full duration as he would be missing out on vital damage, not the mention even if he wanted to, it can be forcefully broken by crowd control.
Frankly, Yi doesn’t need more damage, he already had a great deal. The only time the extra damage from W would actually come into play would be in the jungling / laning phase where Master Yi actually does channel the full ability.
Master Yi is in a very bad spot currently with negative win rates across the various divisions. While he is considered an easier champ and can snowball out of control, this is certainly not his time.