Basic attacks on champs reduce E cooldown by 0.5 seconds. (E is a ~7 second cooldown at max rank/CDR)
Minor, but will give incentive for yuumi's to actually pop out and harass with auto attacks more often in lane, when they're safe, etc.
Just a way to get people thinking about more actions they can make, and start doing more things with yuumi in general.
I feel like her poor winrate is people don't feel obligated to do much besides use her basic abilities/passive every now and then and just afk for the other 60% of the time. They need a little something to get them playing with the same APM they would any other champ.
Also her recommended items are dumb. Changing those would also be a huge buff for new players.